3. Contents
Topic
Topic 1
Topic 2
Topic 3
Topic 4
Topic 5
Page Number
General Physics
Past Paper Questions
Thermal Physics
Past Paper Questions
Waves
Past Paper Questions
Electricity & Magnetism
Past Paper Questions
Atomic Physics
Past Paper Questions
Appendix
Syllabus
2
26
70
83
108
120
146
173
214
221
234
1
4. Topic 1:
General Physics
1
Length
•
Length is a distance measurement and its SI unit is
the metre (m).
•
Length is usually measured with a rule, a tape or a
trundle wheel.
•
Small lengths are measured with a micrometer or
callipers where a greater precision is available.
•
In certain circumstances, average lengths can be
found be measuring a number of distances together
then dividing by the number of objects eg a ream of
paper.
2
Time
•
Time is usually measured with a stopclock. Human
timing is not precise because of reaction times.
•
The SI unit for time is seconds (s).
•
For repeated events, an average time can be found
by measuring a number of repeats then dividing by
the number of cycles eg. a pendulum.
3
2
5. Speed
•
Speed tells us how fast something is moving.
•
It is measured in m/s.
•
Average speed is calculated using:
Average Speed (m s) =
Distance moved (m)
time taken (s)
4
Examples
•
A sprinter runs 100m in 10s. Calculate his average speed.
•
A bird flies 60m in 5s. Calculate its average speed.
•
Pupils measured their times taken to travel different
distances doing various exercises. Their results are recorded
in the table. Complete the table.
Exercise
Distance (m)
Time (s)
Running
70
12
Walking
10
35
Hopping
50
Speed (m/s)
110
5
Acceleration
•
Acceleration tells us how quickly something is changing
its speed.
•
It is measured in m/s2.
•
Acceleration is calculated using:
Average Acceleration (m s 2 ) =
Change in speed ( m s )
time taken (s)
Example:
•
A motorbike goes from 10m/s to 35 m/s in 8s. Calculate
his acceleration
6
3
6. Distance/time graphs
•
A Distance/time graph is a way of representing
motion.
distance
Acceleration
stationary
Constant speed (fast)
Constant speed (slow)
time
7
Calculations with distance/
time graphs
•
Speed is given by the gradient of the distance/time
graph.
8
Distance/time graph questions
•
Describe the motion of the following bodies:
(a)
(b)
d
(c)
d
t
d
t
t
9
4
7. Distance/Time Graph
questions
• Calculate the speeds of the car and the bike
below:
Distance (m)
500
375
Car
Bike
250
125
0
0
5
10
15
20
25
10
Time (s)
Speed/time graphs
• A Speed/time graph is an alternative way
of representing motion.
speed
Non-Uniform
Acceleration
Constant speed
Rapid acceleration
Gradual acceleration
Stationary
time
11
Calculations with speed/time
graphs
•
Acceleration is given by the gradient of the speed/
time graph.
•
Distance is given by the Area under the speed/time
graph.
12
5
8. Speed/time graph questions
Describe the motion of the following
bodies:
•
(a)
(b)
v
(c)
v
v
t
t
t
13
Speed/time calculation.
•
(a) Find the acceleration of the bike in the first 10s.
•
(b) Find the distance moved by the bike in the first 20s.
Motion of a bike
15.00
Speed (m/s)
11.25
7.50
3.75
0
0
5
10
15
20
14
time (s)
The Ticker-Timer
Ticker Tape
Ticker Timer
• The ticker-timer runs at 50Hz. It puts 50 dots on
the tape every second.
• If the tape moves quickly, the dots are widely
spaced.
• If the tape moves slowly, the dots are close
15
6
9. Ticker Tape
Slow moving ticker-tape
Fast moving ticker-tape
16
Charts
•
By cutting the tape into 5 space strips and arranging them
side-by-side we can get a chart representing the motion.
•
Each strip will represent 0.1s of motion.
17
Typical Shapes of Charts
18
7
10. Calculations
•
Since each strip represents 0.1s of motion, and we
can measure the length of the strips in cm, we can
use speed=distance/time to calculate the speeds.
19
Scalars and Vectors
•
A SCALAR quantity has a size (Magnitude), but no direction.
•
Examples of scalar Quantities are temperature, time, energy and power.
•
A VECTOR quantity has both a magnitude and a direction. Vectors
are often represented with an arrowed line. The direction of the arrow
is the direction of the vector and the length of the line represents the
size of the vector.
•
Examples of vectors are force, momentum and velocity.
F
20
2
1
Big
Stone
Small
Stone
Paper
Tray
3
Small
Stone
Paper
Coin
Vacuum
Sand
Bucket
Sand
Bucket
21
8
11. Gravity
•
Experiment 1
•
•
•
Both Stones Land at the same time.
Gravity makes them fall at the same rate.
Experiment 2
•
•
•
Stone landed first.
Air Resistance slowed down the paper tray.
Experiment 3
•
Both coin & paper land at the same time.
22
Weight and Mass
•
Weight is a force. It tells us how heavy something
is. It is measured in newtons (N). It changes
depending upon the size of gravity. (Trip to the
moon)
•
Mass tells us how much substance there is in an
object. It is measured in kilograms (kg). It never
changes.
•
On Earth we multiply mass by 10 to get weight.
23
Density
•
Density tells us how compact the mass is in a material.
•
It is given by:
Density ( kg m 3 ) =
mass(kg)
volume(m 3 )
or
Density ( g cm 3 ) =
mass(g)
volume(cm 3 )
•Stick to one set of units.
•Water has a density of 1000 kg/m3 or 1 g/cm3.
•Materials with a smaller density than water will float,
materials with a higher density than water will sink.
24
9
12. Density Calculation
Complete the following table:
Object
Density (kg/
m3)
B
2000
2
8000
C
Volume (m3)
4000
A
Mass (kg)
D
4
1000
2000
4
a) Which object has the greatest mass?
b) Which has the smallest volume?
c) Which objects could be made of the same substance?
d) Which object would float on water?
25
Irregular objects
•
The volume of a liquid can be determined using a
measuring cylinder.
•
The volume of irregular objects has to be found by
displacement.
26
Hooke’s Law
•
Hooke’s Law states that the extension in a spring is
proportional to the load applied.
load α extension
or
F = kx
The constant of proportionality is called the Spring
Constant.
27
10
13. Extension/Force Graphs
•
A graph can be plotted to show how Force varies
with extension for a spring.
•
The graph shows proportionality up to a point
called the ‘proportionality limit’.
•
With increased extension, the spring will reach a
point at which it will not return to its original shape.
This is called the elastic limit. The spring shows
‘plastic’ behaviour beyond here.
28
Load/Extension Graphs
•
A graph can be plotted to show how extension varies
with load for a spring.
•
The graph shows proportionality up to a point
called the ‘proportionality limit’.
•
With increased load, the spring will reach a point at
which it will not return to its original shape. This is
called the elastic limit. The spring shows ‘plastic’
behaviour beyond here.
29
Extension/Force Graphs
extension
Proportionality
Limit
Linear Region
0
Load
30
11
14. Newton’s 1st Law
•
If the forces around an object balance (resultant
0N), then it will either:
•
Remain at rest
or
•
•
Move at a constant speed in a straight line.
(This is the same as saying constant velocity).
31
Examples of 1st Law
Normal
Normal
Air
Air
Gravity
Gravity
Remains at rest
Moves at a
constant speed
in a straight
line
32
Oil Tube Experiment
Fluid
Resistance
Falls at a
constant
speed in a
straight line.
Gravity
33
12
15. Unbalanced Forces
• If the forces around an object do not balance, then
they will cause the object to accelerate (or
decelerate).
• The rate of the acceleration depends upon the
mass of the object.
• The quantities are linked by the following
equation:
F(N ) = m(kg) × a(m s 2 )
34
Questions
•
1. What will be the Force needed to produce an
acceleration of 2m/s2 on a mass of 4kg?
•
2. What will be the Force needed to produce an
acceleration of 5m/s2 on a mass of 42kg?
•
3. What will be the acceleration produced when a
Force of 50N acts upon a mass of 10kg?
35
Newton’s Laws Calculation
P
6000 N
Q
400 N
10 000 N
A front wheel drive car is travelling at constant velocity. Q is the force of the air on the moving car.
P is the total upward force on both front wheels.
(a) Explain why P= 4 000N, Q= 400N
(b) Calculate the mass of the car.
(c) The 400 N driving force to the left is suddenly doubled.
(i) Calculate the resultant forward driving force.
(ii) Calculate the acceleration of the car.
(iii) Sketch a graph showing how the velocity of the car changes with time (start the graph just
before the driving force is doubled.)
13
36
16. Circular Motion
•
When an object is moving in a circle, it must be experiencing a
force TOWARDS THE CENTRE of the circle.
•
We call this the CENTRIPETAL Force.
•
This should not be confused with CENTRIFUGAL Force.
•
The centripetal force is directed at right angles to the object’s
velocity.
object’s path
direction of force
37
Questions
•
For each of the following examples, draw a sketch to
show the situation, name the force providing the
circular motion, and indicate its direction:
•
A) The Earth orbiting the Sun.
•
B) A car rounding a bend.
•
C) A hammer-thrower winding into his throw.
38
Moments
•
A moment is a turning force.
•
It is given by:
Moment(Nm) = Force(N ) × distance(m)
39
14
17. Example
•
Calculate the moment produced:
0.1m
100N
40
The Principle of Moments
•
If a lever is balanced (in equilibrium) then the total
clockwise moments equal the total anti-clockwise
moments. It will not move.
•
Because of Newton’s 1st Law, the forces must also
balance.
Clockwise
moments
Anti-clockwise
moments
41
Results
Left-Hand Side
Right-Hand Side
Weight
Distance
8
4
?
3
4
?
6
5
2
2
?
6
3
?
2
Weight
Distance
2
Wxd
Wxd
42
15
18. Moments Questions
•
1. Explain why a mechanic would choose a long-arm
spanner to undo a tight nut.
•
2. In the following diagram, what is the weight of X ?
20 cm
X
25 cm
4N
43
Uses of Levers
•
Spanner
•
Nutcracker
•
Scissors
44
Centre of Mass
•
Centre of mass is the point on an object that is the
‘average’ position of the mass of the object.
•
The centre of gravity is a point on all objects through
which forces appear to act.
•
The two points are the same.
•
The centres of mass of regular objects are obvious. They
always lie on a line of symmetry.
•
They are the point under which we place a pivot to balance
the object.
45
16
19. Regular Objects
46
Stability
•
Stability tells us how secure something is on the ground.
•
If something is stable, then it will not topple easily.
•
There are two factors to consider when changing the
stability of an object:
•
•
•
The area of the object’s base.
The position of the centre of mass of the object.
A stable object will have a BIG base, and a LOW centre of
gravity.
47
Simple Addition
•
If two vectors are parallel, then they can be simply
added or subtracted to give a resultant.
3N
5N
RESULTANT
2N
48
17
20. 2D-Addition
•
If the vectors are not parallel we have to draw a scale
diagram and add the vectors to give a resultant.
RESULTANT
3m/s
2m/s
2m/s
3m/s
49
Examples
• 1. A plane flies North at 40m/s. The wind
blows to the East at 15 m/s. Calculate the
overall velocity.
• 2i). A falling ball has a weight of 10N and
and air resistance of 2N. What the effective
downward force on it?
• ii) A wind blows to the left with a force of
2N. Using a vector diagram, calculate the
resultant force on the ball.
50
Heat
Sound
Kinetic
Electricity
Elastic
Potential
Energy
Energy
Forms
Light
Gravitational
Potential
Energy
Chemical
Potential
Energy
51
18
21. Energy Transfers
•
When any physical process takes place, there is a transfer
of energy from one form to another.
•
This can be shown in an energy flow diagram:
Light
Electricity
T.V
Sound
Heat
52
Examples of Energy Transfers
•
A burning match
•
A lightbulb
•
A petrol lawnmower
•
A car
•
Headphones
•
A microphone
•
A waterfall
53
Kinetic Energy
• All objects that are moving have kinetic energy.
• It depends on the mass of the object and its speed.
• It is measured in joules.
KE =
1 2
mv
2
54
19
22. Gravitational Energy
• Gravitational energy is stored in objects that
are at a height.
• It depends upon the mass of the object, and
how high the object is.
• It measured in joules.
GPE = mgh
55
The Principle of the
Conservation of Energy
•
Energy cannot be created or destroyed, it simply
moves from one form to another.
•
When energy moves from one form to another, the
total AMOUNT of energy remains the same.
•
A certain amount of heat energy is always lost to the
surroundings in any process.
56
Efficiency
•
Efficiency tells us how effective a process or energy transfer is.
•
The more useful energy that is produced, for the least input energy, the
more efficient the process is.
•
Efficiency has no unit, and can be expressed as a decimal or percentage.
•
It can be the ratio of power output to input, or energy output to input
for a process
Efficiency =
output
(×100)
input
57
20
23. Work Done
• Work is a type of energy change and is measured
in Joules.
• For work to be done, a force must be acting upon
an object as it moves through a distance.
• The Work Done is given by:
Work Done (J )=Force(N ) × Distance(m)
58
Power
• Power is the rate at which energy is transferred.
• It is also the rate at which Work is done.
• The unit for Power is Watts (W).
• Power is calculated from either:
Power(W )=
Energy Change(J )
Time Taken(s)
or
Power(W )=
Work Done(J )
Time Taken(s)
59
Calculating Personal Power
height
time
weight
•
Measure your weight in newtons.
•
Measure the height of the steps in metres.
•
Measure the time taken to climb the steps in seconds.
•
Calculate the Work Done in joules.
•
Calculate the Power of your legs in Watts.
60
21
24. Pressure
•
Pressure tells us how concentrated a force is.
•
It is calculated from:
Pressure( N m 2 )=
Force(N )
Force(N )
2
or Pressure( N cm )=
2
Area(m )
Area(cm 2 )
Stick to one set of units
61
Examples
2cm
1cm
20g
1cm
1.
Calculate the Volume of the block.
2.
Calculate the block’s density.
3.
Calculate the block’s weight.
4. Calculate the area in contact with the ground.
62
Examples
•
Why do camels have large flat feet?
•
Why is it easier to walk in snow shoes in the snow?
63
22
25. Pressure in Liquids
Pressure in a liquid is due to
the weight of the liquid
above a point.
Pressure increases with
depth.
Pressure will also increase
with density of liquid
(more weight).
P = ρ gd
We can calculate pressure
from:
64
Direction
•
The pressure in a liquid acts
in ALL directions equally at a
point.
•
This is why bubbles are
spherical.
65
Questions
•
1a). Draw a diagram of the cross section of a dam.
•
b) Explain why it has this shape.
•
2. Calculate the pressure on a scuba diver at a depth
of 20m. (The density of water is 1000kg/m3)
•
3. Describe a demonstration to show that Pressure
increases with depth in a liquid.
66
23
26. Non-Renewable Energy
Resources
•
Non-Renewable resources are resources that are
used up and cannot be easily replaced. Examples are
fossil fuels and Nuclear fuels.
67
Renewable Energy Resources
•
Renewable Energy Resources are energy resources
that keep running and do not run-out easily.
68
•
Nuclear Fusion
Safety
•
Pollution
•
Problems
Energy usage
• Transport
• Electricity
The Energy
Crisis
• Fossil Fuels
• Pollution
• Depletion
Renewable
Alternatives
•
Advantages
•
Unreliable
•
Not Controllable
•
Energy Density
Nuclear Fission
•
Energy
Density
• Pollution
•
Safety
69
24
27. General Physics
Quantity and
symbol
Scalar Quantities
Vector Quantities
Average Speed, s
Velocity
Acceleration, a
Mass, m
Weight, W, F
Density, ρ
Force, F
Load, (Hookes
law)
Moment
Equilibrium
Work done, W, E
Kinetic energy,
KE
Definition/Word equation
Scalar quantities only have a magnitude.
Vector quantities have a magnitude, a direction
and a point of application.
Speed is the rate of change of distance. It is a
scalar quantity.
Speed = Total distance
Total time
For constant acceleration situations, the
average speed is also equal to the average of
the initial and final speeds.
s = initial speed + final speed
2
Velocity is the rate of change of displacement.
It is speed in a given direction. A vector
quantity.
Acceleration is the rate of change of velocity.
Acceleration = Final velocity – initial velocity
Time
Mass is a property of a body that resists change
in motion.
Weight is the force on a mass due to the
gravitational field of the Planet. It changes
from planet to planet. Weights can be
compared using a balance.
Weight = mass x acceleration due to gravity
Weight = mass x gravitational field strength
Density is the mass per unit volume.
Density = mass
volume
A force is a push or a pull; it can change the
shape, direction, and/or speed of an object.
Force = mass x acceleration
Load = spring constant x extension
Load α extension
A moment is the turning affect of a force.
Moment = force x perpendicular distance from
the pivot
When there is no resultant force AND no
resulting turning affect, a system is in
equilibrium.
Work done = Force x distance in the direction
of the force = change in energy
Kinetic energy is the energy of a body due to
its motion.
Kinetic energy = ½ x mass x velocity2
25
Symbol
equation
Units
s=d
t
s=u+v
2
m/s
cm/s
km/h
m/s
cm/s
km/h
a= v–u
t
m/s2
W=mxg
Newtons,
N
ρ=m
V
Kg/m3
g/cm3
F=ma
Newtons,
N
F=kl
F α l
Newtons,
N
Moment = F d
Nm
W = F d = ΔE
Joules, J
KE = ½ m v2
Joules, J
28. Gravitational
energy, GPE
Efficiency
Power, P
Gravitational potential energy is the energy of
a body due to its position in the gravitational
field.
Gravitational energy =mass x acceleration due
to gravity x height gained/lost
Efficiency = useful output x 100%
total input
Power is the rate at which energy is converted.
Power = work done
time taken
Power = energy change
time taken
GPE = m g h
%
P=E
t
Pressure, p, P
Pressure = force
area
P=F
A
Fluid Pressure, p,
P
Pressure = density of fluid x acceleration due
to gravity x height of fluid above
P=ρgh
26
Joules, J
Watts, W
N/m2
Pascals,
Pa
millibar
N/m2
Pascals,
Pa
Millibar
30. 2
11. The diagram shows the level of liquid in a measuring cylinder.
cm3
30
liquid
20
What is the volume of the liquid?
A
24 cm3
B
28 cm3
C
29 cm3
D
32 cm3
2 A cylindrical can is rolled along the ruler shown in the diagram.
2.
final position
starting position
can rolled
mark on
can
0 cm
5
10
15
20
The can rolls over twice.
What is the circumference (distance all round) of the can?
A
13 cm
B
14 cm
C
26 cm
D
0625/1/M/J/02
28
28 cm
25
30 cm
31. 3
33. The graph shows how the speed of a car changes with time.
Q
speed
P
O
R
time
Which of the following gives the distance travelled in time interval OR?
A
the area OPQR
B
the length PQ
C
the length (QR – PO)
D
the ratio QR/PO
4
4. A snail crosses a garden path 30 cm wide at a speed of 0.2 cm/s.
movement
of snail
30 cm
snail
How long does the snail take?
A
5.
5
B
0.0067 s
6.0 s
C
15 s
D
150 s
What are correct units used for mass and for weight?
mass
weight
A
kg
kg
B
kg
N
C
N
kg
D
N
N
0625/1/M/J/02
29
[Turn over
32. 4
66. Two objects X and Y are placed on a beam as shown. The beam balances on a pivot at its
centre.
Y
X
pivot
What does this show about X and Y?
A
They have the same mass and the same density.
B
They have the same mass and the same weight.
C
They have the same volume and the same density.
D
They have the same volume and the same weight.
7. A shop-keeper places two identical blocks of cheese on a set of scales and notices that their
7
combined mass is 240 g. Each block measures 2.0 cm x 5.0 cm x 10.0 cm.
g
What is the density of the cheese?
A
0.42 g / cm3
B
0.83 g / cm3
C
1.2 g / cm3
D
2.4 g / cm3
8
8. The table shows the length of a wire as the load on it is increased.
load / N
length / cm
0
50.0
10
20
30
52.1
54.1
56.3
Which subtraction should be made to find the extension caused by the 20 N load?
A
54.1 cm – 0 cm
B
54.1 cm – 50.0 cm
C
54.1 cm – 52.1 cm
D
56.3 cm – 54.1 cm
0625/1/M/J/02
30
33. 5
99. A child tries to push over a large empty oil drum.
Where should the drum be pushed to topple it over with least force?
A
B
C
D
10. Which device is designed to convert chemical energy into kinetic energy (energy of motion)?
10
A
an a.c. generator
B
a battery-powered torch
C
a car engine
D
a wind-up mechanical clock
11. A ball is released from rest and rolls down a track from the position shown.
11
What is the furthest position the ball could reach?
C
ball
starts
here
B
D
A
0625/1/M/J/02
31
[Turn over
34. 6
12 Two sharp nails and two blunt nails are held on a piece of wood. Each nail is hit with the same
12.
hammer with the same amount of force.
When it is hit, which nail causes the greatest pressure on the wood?
A
B
hammer
sharp nails
C
D
hammer
blunt nails
13.
13 The diagram shows a manometer connected to a container of carbon dioxide.
container
carbon dioxide
5 cm
mercury
manometer
Which statement correctly describes the pressure exerted by the carbon dioxide?
A
It is equal to the atmospheric pressure.
B
It is equal to 5 cm of mercury.
C
It is equal to 5 cm of mercury above atmospheric pressure.
D
It is equal to 5 cm of mercury below atmospheric pressure.
0625/1/M/J/02
32
35. 2
14. A glass tank contains some water.
1
V
water
T
Q
U
S
R
The length QR and the width RS of the tank are known.
What other distance needs to be measured in order to be able to calculate the volume of the
water?
A
B
ST
C
SV
D
TU
TV
2
15. A stopwatch is used to time a race. The diagrams show the watch at the start and at the end of the
race.
start
55
end
60
5
55
10
50
40
35
30
45.7 s
B
46.0 s
15
40
25
C
46.5 s
D
0625/01/M/J/03
33
47.0 s
20
seconds
35
How long did the race take?
A
10
45
20
seconds
5
50
15
45
60
30
25
36. 3
16. The diagram shows a speed-time graph for a body moving with constant acceleration.
3
speed
0
time
0
What is represented by the shaded area under the graph?
A
acceleration
B
distance
C
speed
D
time
17. A tunnel has a length of 50 km. A car takes 20 min to travel between the two ends of the tunnel.
4
What is the average speed of the car?
A
2.5 km / h
B
16.6 km / h
C
150 km / h
D
1000 km / h
18. Which statement is correct?
5
A
Mass is a force, measured in kilograms.
B
Mass is a force, measured in newtons.
C
Weight is a force, measured in kilograms.
D
Weight is a force, measured in newtons.
0625/01/M/J/03
34
[Turn over
37. 4
6
19. Three children, X, Y and Z, are using a see-saw to compare their weights.
X
Y
Y
Z
X
Z
Which line in the table shows the correct order of the children’s weights?
heaviest
←→
lightest
A
X
Y
Z
B
X
Z
Y
C
Y
X
Z
D
Y
Z
X
20. What apparatus is needed to determine the density of a regularly-shaped block?
7
A
a balance and a ruler
B
a balance and a forcemeter (spring balance)
C
a measuring cylinder and a ruler
D
a measuring cylinder and a beaker
21. A spring is suspended from a stand. Loads are added and the extensions are measured.
8
spring
stand
loads
rule
Which graph shows the result of plotting extension against load?
0
0
load
0
0
0
load
0625/01/M/J/03
35
extension
D
extension
C
extension
B
extension
A
0
load
0
0
load
38. 5
22. A student uses a stand and clamp to hold a flask of liquid.
9
Which diagram shows the most stable arrangement?
A
B
C
D
10 What is the source of the energy converted by a hydro-electric power station?
23.
A
hot rocks
B
falling water
C
oil
D
waves
24.
11 A labourer on a building site lifts heavy concrete blocks onto a lorry. Lighter blocks are now lifted
the same distance in the same time.
What happens to the work done in lifting each block and the power exerted by the labourer?
work done in
lifting each block
power exerted by
labourer
A
decreases
decreases
B
decreases
remains the same
C
increases
increases
D
remains the same
increases
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36
[Turn over
39. 6
25.
12 The diagram shows an instrument used to measure gas pressure.
liquid
What is the instrument called?
A
ammeter
B
barometer
C
manometer
D
thermometer
13 The diagrams show two divers swimming in the sea and two divers swimming in fresh water. Sea
26.
water is more dense than fresh water.
On which diver is there the greatest pressure?
0m
0m
sea water
A
2m
4m
fresh water
C
2m
B
6m
4m
6m
14 When water evaporates, some molecules escape.
27.
Which molecules escape?
A
the molecules at the bottom of the liquid with less energy than others
B
the molecules at the bottom of the liquid with more energy than others
C
the molecules at the surface with less energy than others
D
the molecules at the surface with more energy than others
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37
D
40. 2
1 The diagram shows a me asuring cylinder.
28.
100
90
80
70
60
50
40
30
20
10
Which unit would be most suitable for its scale?
A
mm 2
mm 3
B
cm 2
C
D
cm 3
29. A piece of cotton is me asured betwe en two points on a ruler.
2
cotton
cm
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
When the length of cotton is wound closely around a pen, it goes round six times.
six turns of cotton
pen
What is the distance once round the pen?
A
2.2 cm
U C L E S 2004
B
2.6 cm
C
13.2 cm
0625/01/M/J/04
38
D
15.6 cm
16
44. 6
39.
12 The diagram shows a simple mercury barometer. The barometer re ading is h cm of mercury.
S
h
mercury
40. What is the pressure at S?
A
approximately z ero
B
atmospheric pressure
C
atmospheric pressure + h cm of mercury
D
h cm of mercury
41.
13 Two boys X and Y e ach have the same total weight and are standing on soft ground.
X
Y
Which boy is more likely to sink into the soft ground and why?
boy more
likely to sink
pressure on soft
ground
A
X
larger than Y
B
X
smaller than Y
C
Y
larger than X
D
Y
smaller than X
U C L E S 2004
0625/01/M/J/04
42
55. 2
1
1. A group of students attempts to find out how much power each student can generate. The
students work in pairs in order to find the time taken for each student to run up a flight of
stairs.
The stairs used are shown in Fig. 1.1.
finishing point
starting point
Fig. 1.1
(a) Make a list of all the readings that would be needed. Where possible, indicate how the
accuracy of the readings could be improved.
..........................................................................................................................................
..........................................................................................................................................
..........................................................................................................................................
..........................................................................................................................................
..........................................................................................................................................
..................................................................................................................................... [4]
(b) Using words, not symbols, write down all equations that would be needed to work out
the power of a student.
..........................................................................................................................................
..........................................................................................................................................
..................................................................................................................................... [2]
(c) (i)
When the student has reached the finishing point and is standing at the top of the
stairs, what form of energy has increased to its maximum?
...................................................................................................................................
(ii)
Suggest why the total power of the student is greater than the power calculated by
this method.
...................................................................................................................................
...................................................................................................................................
[3]
0625/3/M/J/02
53
For
Examiner’s
Use
56. 3
For
Examiner’s
Use
2
2. A small rubber ball falls vertically, hits the ground and rebounds vertically upwards.
Fig. 2.1 is the speed-time graph for the ball.
10
B
speed
8
m/s
6
D
4
2
0
A
0
E
C
0.5
1.0
1.5
time / s
2.0
Fig. 2.1
(a) Using information from the graph, describe the following parts of the motion of the ball.
(i)
part AB
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
(ii)
part DE
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
[3]
(b) Explain what is happening to the ball along the part of the graph from B through C to D.
..........................................................................................................................................
..........................................................................................................................................
..................................................................................................................................... [2]
(c) Whilst the ball is in contact with the ground, what is the
(i)
overall change in speed,
change in speed = ........................................
(ii)
overall change in velocity?
change in velocity = ......................................
[2]
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54
[Turn over
57. 4
(d) Use your answer to (c) to explain the difference between speed and velocity.
..........................................................................................................................................
..........................................................................................................................................
..................................................................................................................................... [2]
(e) Use the graph to calculate the distance travelled by the ball between D and E.
distance travelled = ..................................[2]
(f)
Use the graph to calculate the deceleration of the ball between D and E.
deceleration = ..................................[2]
0625/3/M/J/02
55
For
Examiner’s
Use
58. 2
1
3. Fig. 1.1 shows apparatus that may be used to compare the strengths of two springs of the
same size, but made from different materials.
spring
scale
masses
Fig. 1.1
(a) (i)
Explain how the masses produce a force to stretch the spring.
...................................................................................................................................
(ii) Explain why this force, like all forces, is a vector quantity.
...................................................................................................................................
...................................................................................................................................
[2]
(b) Fig. 1.2 shows the graphs obtained when the two springs are stretched.
force/N
20
spring 1
15
spring 2
10
5
0
0
10
20
30
extension/mm
Fig. 1.2
0625/3/M/J/03
56
40
For
Examiner’s
Use
59. 3
(i)
State which spring is more difficult to extend. Quote values from the graphs to
support your answer.
For
Examiner’s
Use
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
(ii)
On the graph of spring 2, mark a point P at the limit of proportionality. Explain your
choice of point P.
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
(iii)
Use the graphs to find the difference in the extensions of the two springs when a
force of 15 N is applied to each one.
difference in extensions = ..................................
[6]
24. The speed of a cyclist reduces uniformly from 2.5 m/s to 1.0 m/s in 12 s.
(a) Calculate the deceleration of the cyclist.
deceleration = ..................................[3]
(b) Calculate the distance travelled by the cyclist in this time.
distance = ..................................[2]
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57
[Turn over
60. 4
3
5. Fig. 3.1 shows the arm of a crane when it is lifting a heavy box.
1220 N
950 N
40° 30°
P
box
Fig. 3.1
(a) By the use of a scale diagram (not calculation) of the forces acting at P, find the weight
of the box.
[5]
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58
For
Examiner’s
Use
61. For
Examiner’s
Use
5
(b) Another box of weight 1500 N is raised vertically by 3.0 m.
(i)
Calculate the work done on the box.
work done = ..................................
(ii)
The crane takes 2.5 s to raise this box 3.0 m. Calculate the power output of the
crane.
power = ..................................
[4]
4
Fig. 4.1 shows a sealed glass syringe that contains air and many very tiny suspended dust
particles.
syringe
seal
piston
dust particles
Fig. 4.1
(a) Explain why the dust particles are suspended in the air and do not settle to the bottom.
..........................................................................................................................................
..........................................................................................................................................
..........................................................................................................................................
......................................................................................................................................[3]
(b) The air in the syringe is at a pressure of 2.0 × 105 Pa. The piston is slowly moved into the
syringe, keeping the temperature constant, until the volume of the air is reduced from
80 cm3 to 25 cm3. Calculate the final pressure of the air.
pressure = ..................................[3]
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59
[Turn over
73. Topic 2:
Thermal Physics
1
Solids
• The particles in solids are tightly held together by strong
forces.
• They vibrate around mean positions.
• The higher the temperature, the more vibrational kinetic
energy the particles have.
• Solids have a rigid shape.
2
Liquids
• In liquids the forces are strong, but the vibrating
particles are not fixed in position.
• The particles can move but they are held close to their
neighbours.
• Liquids do not keep their shape.
3
71
74. Gases
• In gases the forces are very weak and they are virtually
free to move around their container.
• The particles occasionally collide.
• Gases expand to fill their container.
• The collisions between the particles and the container
walls provides pressure.
4
Changing State
• When a material changes from one state to another,
bonds are either broken or created.
• When bonds are broken, heat must be supplied. When
bonds are created, heat is released.
• When materials change state there is no change in the
temperature.
5
Phase Changes
• The phase change from solid to liquid is called ‘fusion’.
• The phase change from liquid to gas is called
‘vaporisation’.
• The energy required to effect the phase change is called
the ‘Latent Heat’.
• The Latent Heat required per kg is called the ‘Specific
Latent Heat’.
6
72
75. Phases Changes (Graphical)
vaporisation
Temperature
liquid
water
fusion
Time
7
Latent Heat Calculations
• The Specific Latent Heat of a material is given the symbol l.
• From the definition, we have the following relationship:
H = ml
H-J
m - kg
l - J/kg
8
Heat Capacity
• Whilst a material is being heated within a certain state
of matter, its temperature will rise.
• The temperature rise depends upon the mass of the
material, the type of material and the amount of heat
supplied.
• The property of a material that represents how much
heat is needed to raise its temperature is called its
‘Specific Heat Capacity’ and is given the symbol c.
9
73
76. Calculations
• To calculate heat required we use:
H = mcΔT
H-J
m - kg
C - J/kg/
ºC
∆T - ºC
10
Constant Volume
• If we increase the temperature of a gas in a
container at a constant volume, the particles
will move with more energy, and so there will
be more collisions, and so greater pressure:
Pressure increases with Temperature
11
Constant Pressure
•
If we increase the temperature of a gas in a container at
a constant pressure, the particles will move with more
energy, but they need more space to keep the collisions
constant and so there will be a greater volume:
Volume increases with Temperature
12
74
77. Constant Temperature
•
If we keep the temperature of a gas constant, we
keep the kinetic energy of the particles constant.
•
Decreasing the volume of the gas’ container will
increase the number of collisions of the particles with
the container.
•
The pressure of the gas will increase.
•
Pressure and Volume changes are described by the
following relationship:
P1V1 = P2V2
13
Brownian Motion
•
When pollen grains are placed on the surface of a
liquid and a strong light source is used to illuminate
the pollen, the pollen is seen to move randomly.
•
This movement is called ‘Brownian Motion’ and
cause by the invisible water particles hitting the
pollen grains.
14
Expansion
•
When particles are heated they gain energy.
•
They become more spaced-out, and the material gets bigger.
•
We say that the material expands.
•
Generally, objects expand as they get hotter and contract as they get cooler.
•
Liquids expand more than solids on heating, and gases expand more than liquids.
•
Solids expand with the greatest force. Gases expand with the least force.
15
75
78. Questions on Expansion
•
Why do walls have expansion joints?
•
Why are pylon electrical cables tighter in winter?
•
Why do railway lines leave regular gaps between
them?
16
Temperature Scales
•
The most common temperature scale that is used is the
Celsius scale. This has its zero at the freezing point of water,
and the boiling point of water is 100°C.
•
In Physics, the Kelvin scale (or Absolute Temperature scale) is
often used.
•
This is often more sensible as the zero is defined as the point
at which the particles have no kinetic energy (Absolute Zero).
•
To convert between Celsius and Kelvin, we add 273°C.
•
A rise of 1K is the same as a rise of 1°C.
17
Internal Energy
• The Kelvin Temperature is proportional to
the average kinetic energy of the particles.
18
76
79. Evaporation
• Evaporation is a process by which a liquid
cools due to the fact that particles are lost
from its surface.
• The higher energy particles will be more
likely to leave the liquid, so lowering the
average KE of the particles remaining in the
liquid. The temperature will thus be
lowered.
• Increasing the exposed surface area of the
liquid, or increasing the movement of air will
increase the rate of evaporation.
19
Changing State
When a material changes from one state to another,
bonds are either broken or created. This involves an
associated Internal Energy change.
When bonds are broken, heat must be supplied.
When bonds are created, Heat is released.
Since the energy changes are entirely Internal, there
is no change in kinetic energy of the particles, and
hence no change in the temperature of the material.
20
Thermometry
To make a thermometer, we need a property that
changes with temperature in a linear fashion.
We then need to calibrate the thermometer by
choosing two fixed points.
The fixed points for calibration are the boiling point
of water (100°C) and the freezing point of water
(0°C).
The scale is then divided into 100 equal parts for
interpolation.
21
77
80. Liquid in Glass Thermometers
•
Liquid in glass thermometers have liquid in
a glass bulb. As the liquid is heated it
expands and its level rises up the scale.
•
The choice of liquid, the thinness of the
bore or the size of the bulb will affect the
sensitivity of the thermometer.
•
The choice of liquid will affect the range of
the thermometer.
22
Thermocouple
•
A thermocouple is a junction of two different metals.
•
Electrons will move across the junction creating a measurable voltage.
•
The higher the temperature, the more energy the electrons will have, more
electrons will move and we get a greater voltage.
•
The voltage is then calibrated.
•
High temperatures can be quickly recorded.
23
Heat Transfer
•
Heat flows from hot areas to cold areas.
•
In solids, heat moves by conduction.
•
In liquids and gases (fluids), heat moves by
convection.
•
In a vacuum heat has to move by radiation.
24
78
81. Conduction
Heat
Heat
•
Heat moves from particle to particle as they collide.
•
Poor conductors are called insulators.
•
Solids are the best conductors (especially metals).
•
Gases are the best insulators.
25
Questions on Conduction.
1. Why does a robin fluff up its feathers in Winter?
2. Why is a string vest warmer than a cotton vest?
3. Design an experiment to compare conductors.
26
Convection
Cool fluid in
a beaker.
Convection
currents
circulate the
heat.
Heat source
is applied.
Warm fluid
expands and
rises. (low
density)
Denser Cool
fluid sinks
Heat
27
79
82. Questions on Convection
•
Why should you stay close to the ground in a smokefilled room?
•
Why is the heating element at the bottom of a kettle?
28
Radiation
Hot object
(warmer than
surroundings).
Infra-red
light energy
emitted..
Cooler
object
29
Radiation
•
Black objects are better radiators and absorbers than
white or shiny objects.
•
Rough objects are better radiators and absorbers than
shiny or smooth objects.
30
80
83. Questions on Radiation
•
Why are houses often painted white in hot
countries?
•
Why do marathon runners wear an aluminium
blanket at the end of a race?
31
The Vacuum Flask
stopper
silver
surface
vacuum
32
81
84. 1
Thermal Physics
Quantity and
symbol
Symbol
equation
Definition
The temperature of a gas is related to the
motion of its particles. The faster, and
Temperature, T, θ
therefore the more energetic the particles
the hotter the gas.
The random, jerky motion of particles
(pollen in water, smoke in air) in a
Brownian Motion suspension is evidence for the kinetic model
of matter. The massive particles are moved
by light, fast moving molecules.
The more energetic molecules escape from
the surface of a liquid. This leaves the
Evaporation
liquid left behind with a lower average KE,
and hence a cooler liquid.
For a fixed mass of gas, the pressure is
Pα1
inversely proportional to the volume, (at
V
Boyles’ Law
constant temperature)
PV = k
For a fixed mass of gas, the volume is
VαT
Charles’ Law
directly proportional to the temperature, (at
V=kT
constant pressure)
For a fixed mass of gas, the pressure is
PαT
directly proportional to the temperature, (at
P=kT
Pressure Law
constant volume)
For a fixed mass of gas, the
PV = k
Pressure x Volume = a constant
T
Gas Law
Temperature
P1V1 = P2V2
T1
T2
The amount of heat energy required to
c=E
Thermal Capacity, c
change the temperature of a body by 1 oC
ΔT
The amount of heat energy required to
c=Q
Specific Heat
change the temperature of a unit mass of a
mΔT
Capacity, c
o
substance by 1 C
The amount of energy required to change
Latent Heat, L
the state of a body without a change in
temperature
The amount of energy required to change
L=Q
Specific Latent Heat the state of unit mass of substance, from
m
of Fusion, L
solid to liquid without a change in
temperature
The amount of energy required to change
L=Q
Specific Latent Heat the state of unit mass of a substance from
m
of Vaporisation, L liquid to gas without a change in
temperature
The movement of heat energy by the
passing on of vibrations from particle to
Conduction
particle.
82
units
o
C, K
Temperature
must be the
absolute
temperature
in Kelvin,
K.
The other
quantities
must be
consistent.
J/ oC
J/kg oC
Jkg oC
J
J/kg
J/g
J/kg
J/g
85. 2
Convection
Radiation
The movement of heat energy by the mass
movement of fluids, due to expansion and
density changes due to heating.
The movement of heat energy by the form
of an electromagnetic wave. (Infrared)
83
87. 7
1.
14 The diagram represents molecules in a liquid.
A and C are molecules with a high amount of energy.
B and D are molecules with a low amount of energy.
Which molecule is most likely to be leaving the liquid by evaporation?
A
B
D
C
15 The size of a balloon increases when the pressure inside it increases.
2.
The balloon gets bigger when it is left in the heat from the Sun.
cool balloon
hot balloon
Why does this happen?
A
The air molecules inside the balloon all move outwards when it is heated.
B
The air molecules inside the balloon are bigger when it is heated.
C
The air molecules inside the balloon move more quickly when it is heated.
D
The number of air molecules inside the balloon increases when it is heated.
3.
16 What must expand in order to show the temperature rise in a mercury-in-glass thermometer?
A
the glass bulb
B
the glass stem
C
the mercury
D
the vacuum
0625/1/M/J/02
85
[Turn over
88. 8
4.
17 The table shows the melting points and boiling points of four substances.
Which substance is a liquid at a room temperature of 20 oC?
substance
melting point / oC
boiling point / oC
A
–101
–35
B
–39
357
C
30
2100
D
327
1750
18 A bar made of half wood and half copper has a piece of paper wrapped tightly round it.
5.
The bar is heated strongly at the centre for a short time, and the paper goes brown on one side
only.
wood paper copper
heat
Which side goes brown, and what does this show about wood and copper?
brown side
wood
copper
A
copper
conductor
insulator
B
copper
insulator
conductor
C
wood
conductor
insulator
D
wood
insulator
conductor
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86
89. 9
6.
19 The diagrams show part of a water-heating system which is working by convection.
Which diagram shows the most likely flow of water in the system?
A
B
hot
water
tank
hot
water
tank
boiler
boiler
heat
heat
C
D
hot
water
tank
hot
water
tank
boiler
boiler
heat
9
heat
19 The diagram shows a heater used to heat a tank of cold water.
7.
20 A drop of water from a tap falls onto the surface of some water of constant depth.
water
lagging
view from above
tank
heater
Water waves spread out on the surface of the water.
Which statement is true?
A
What is the main process and travel at the same speed in all directions.
The waves are longitudinal by which heat moves through the water?
B
The waves are longitudinal and travel more quickly in one direction than in others.
A conduction
C
The waves are transverse and travel at the same speed in all directions.
B convection
D
The waves are transverse and travel more quickly in one direction than in others.
C evaporation
D
radiation
0625/1/M/J/02
20 What causes refraction when light travels from air into glass?
A
87
The amplitude of the light waves changes.
[Turn over
90. 7
15 Two metal boxes containing air are standing in a room. Box X is on top of a heater. Box Y is on a
8.
bench. The boxes are left for a long time.
Y
X
heater
bench
Which line in the table best describes the average speed of the molecules in the containers?
box X
box Y
A
fast
zero
B
fast
slow
C
slow
fast
D
zero
fast
9.
16 The top of the mercury thread in a mercury-in-glass thermometer reaches point X at 0 °C and
point Z at 100 °C.
Z
Y
X
W
Where might it be at a temperature below the ice-point?
A
point W
B
point X
C
point Y
D
point Z
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88
[Turn over
91. 8
17 The same quantity of heat energy is applied to four different blocks. The temperature rise
10.
produced is shown on each block.
Which block has the highest thermal capacity?
A
B
temperature
rise is
3 °C
temperature
rise is
6 °C
C
D
temperature
rise is
18 °C
temperature
rise is
9 °C
11.
18 A person holds a glass beaker in one hand and fills it quickly with hot water. It takes several
seconds before his hand starts to feel the heat.
Why is there this delay?
A
Glass is a poor conductor of heat.
B
Glass is a good conductor of heat.
C
Water is a poor conductor of heat.
D
Water is a good conductor of heat.
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89
94. 9
15.
18 An experiment is set up to find out which metal is the best conductor of heat. Balls are stuck with
wax to rods made from different metals, as shown in diagram X.
The rods are heated at one end. Some of the balls fall off, leaving some as shown in diagram Y.
Which labelled metal is the best conductor of heat?
diagram X
diagram Y
A
h
e
a
t
B
h
before heating
C
e
a
D
t
after heating
16. Thermometer X is held above an ice cube and thermometer Y is held the same distance below
19
the ice cube. After several minutes, the reading on one thermometer changes. The ice cube does
not melt.
thermometer X
ice cube
thermometer Y
Which thermometer reading changes and why?
thermometer
reason
A
X
cool air rises from the ice cube
B
X
warm air rises from the ice cube
C
Y
cool air falls from the ice cube
D
Y
warm air falls from the ice cube
UCLES 2004
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92
[Turn over
100. 5
3
1.
Fig. 3.1 is an attempt to show the molecules in water and the water vapour molecules over
the water surface.
For
Examiner’s
Use
water vapour
molecules
water molecules
Fig. 3.1
(a) Explain, in terms of the energies of the molecules, why only a few water molecules have
escaped from the water surface.
..........................................................................................................................................
..........................................................................................................................................
..................................................................................................................................... [2]
(b) State two ways of increasing the number of water molecules escaping from the surface.
1 .......................................................................................................................................
2 .................................................................................................................................. [2]
(c) Energy is required to evaporate water.
Explain, in molecular terms, why this energy is needed.
..........................................................................................................................................
..........................................................................................................................................
..................................................................................................................................... [2]
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98
[Turn over
101. 6
42. (a) Fig. 4.1 shows a cylinder containing air at a pressure of 1.0 × 105 Pa. The length of the
air column in the cylinder is 80 mm.
80 mm
air
piston
cylinder
Fig. 4.1
The piston is pushed in until the pressure in the cylinder rises to 3.8 × 105 Pa.
Calculate the new length of the air column in the cylinder, assuming that the
temperature of the air has not changed.
new length = .................................. [3]
(b) Fig. 4.2 shows the same cylinder containing air.
air
Fig. 4.2
The volume of the air in the cylinder changes as the temperature of the air changes.
(i)
The apparatus is to be used as a thermometer. Describe how two fixed points, 0 °C
and 100 °C, and a temperature scale could be marked on the apparatus.
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
(ii)
Describe how this apparatus could be used to indicate the temperature of a large
beaker of water.
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
[5]
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99
For
Examiner’s
Use
102. [4]
4
Fig. 4.1 shows a sealed glass syringe that contains air and many very tiny suspended dust
5
particles.
3. (b) Another box of weight 1500 N is raised vertically by 3.0 m.
(i)
syringe
Calculate the work done on the box.
seal
piston
work done = ..................................
dust particles
(ii)
For
Examiner’s
Use
The crane takes 2.5 s to raise this box 3.0 m. Calculate the power output of the
Fig. 4.1
crane.
(a) Explain why the dust particles are suspended in the air and do not settle to the bottom.
..........................................................................................................................................
..........................................................................................................................................
power = ..................................
[4]
..........................................................................................................................................
4
......................................................................................................................................[3]
Fig. 4.1 shows a sealed glass syringe that contains air and many very tiny suspended dust
particles.
(b) The air in the syringe is at a pressure of 2.0 × 105 Pa. The piston is slowly moved into the
syringe, keeping the temperature constant, until the volume of the air is reduced from
syringe
80 cm3 to 25 cm3. Calculate the final pressure of the air.
seal
piston
pressure = ..................................[3]
dust particles
0625/3/M/J/03
Fig. 4.1
[Turn over
(a) Explain why the dust particles are suspended in the air and do not settle to the bottom.
..........................................................................................................................................
..........................................................................................................................................
..........................................................................................................................................
......................................................................................................................................[3]
(b) The air in the syringe is at a pressure of 2.0 × 105 Pa. The piston is slowly moved into the
syringe, keeping the temperature constant, until the volume of the air is reduced from
80 cm3 to 25 cm3. Calculate the final pressure of the air.
pressure = ..................................[3]
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100
[Turn over
103. 6
54. Fig. 5.1 shows a thermocouple set up to measure the temperature at a point on a solar
panel.
Sun's rays
surface
of solar
panel
Z
X
cold junction
Y
hot junction
Fig. 5.1
(a) X is a copper wire.
(i)
Suggest a material for Y.
...................................................................................................................................
(ii)
Name the component Z.
...................................................................................................................................
[2]
(b) Explain how a thermocouple is used to measure temperature.
..........................................................................................................................................
..........................................................................................................................................
......................................................................................................................................[3]
(c) Experiment shows that the temperature of the surface depends upon the type of
surface used.
Describe the nature of the surface that will cause the temperature to rise most.
..........................................................................................................................................
......................................................................................................................................[1]
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101
For
Examiner’s
Use
112. Transverse Waves
•
In a transverse wave, the wave
motion is at right angles to the
direction of the wave.
•
The Energy flows in a direction at
right angles to the wave motion.
•
Examples of transverse waves are
Light, Pond-ripples, Seismic Swaves.
4
Longitudinal Waves
In a longitudinal wave, the wave motion
is along the direction of the wave. It
consists of a series of compressions and
rarefractions.
The Energy flows in the same direction
as the wave motion.
Examples of longitudinal waves are
Sound and Seismic P-waves.
5
Reflection
•
If waves hit a boundary, they will reflect.
•
The angle of incidence will be equal to the angle of
reflection.
Incident
wavefronts
Reflected
wavefronts
Reflecting
Surface
Normal
6
110
113. Refraction
•
If a wave changes speed, its direction will change.
•
If it slows-down it will bend towards the normal.
•
If the wave speeds-up it will bend away from the normal.
Incident
wavefronts
Boundary
Refracted
Wavefronts
Normal
7
Diffraction
•
If a wave encounters a gap that is of a similar size as the
wavelength of the wave, we will get diffraction.
•
The wave appears to spread-out from the gap.
8
Period of a Wave
• The period of a wave is the time taken for the
wave to complete one cycle.
• There is a simple relationship between Period
(T) and Frequency (f):
Period =
1
frequency
9
111
