Malaysia SPM syllabus Form 5 Physics Chapter 7. Part 2: Electric Current and Potential Difference
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7.2 relationship between electric current and potential difference
1. CHAPTER 7: ELECTRICITY
7.1: Relationship
between electric current
and potential difference
2. What is potential difference?
is connected to a bulb
It creates an electric field along the wires
3. What is potential difference?
The positive terminal at P has a higher potential
The negative terminal at Q has a lower potential
Potential Difference, V
P Q
4. What is potential difference?
and lights the bulb
Potential Difference, V
P Q
5. What is potential difference?
Work is done
When electrical
energy carried
by the charges
is dissipated by
heat
and light energy
after crossing
the bulb
6. Potential Difference Equation
Potential Work Done
Difference, Charge
Or SI Unit:
Joule
Potential Energy
Difference, Charge
12. Ohm’s Law
The electric current, I
flowing through a
conductor is directly
proportional to the
potential difference
across it if the
temperature and other
physical conditions are
constant
17. Resistance
Resistance (R) is defined as the ratio of
potential difference (V) across the
conductor the the current (I) flowing
through it.
18. Disadvantage of Resistance
Causes some
electrical energy to
turn into heat
So some electrical
energy is lost when
trying to transmit
across a conductor
19. Advantage of Resistance
Resistance allows us to use electricity
for heat and light
Heat generated from electric heaters
are due to resistance
Light we get from light bulb is due to
resistance of the wire
- filament becomes hot and glows
21. Super Conductor
Resistance of a metal
increases with temperature
Resistance of a semiconductor
decreases with temperature
22. Super Conductor
A material whose resistance becomes zero when its
temperature drops to a certain value called the critical
temperature
23. Advantages of a superconductor
Enables superconductors
to maintain a current
with no applied voltage
at that temperature
24. Advantages of a superconductor
Able to sustain large currents
25. Advantages of a superconductor
Enables superconductors
to maintain a current
with no applied voltage
at that temperature
26. Advantages of a superconductor
Able to sustain large currents
27. Advantages of a superconductor
Small sized motors and generators can be used
28. MAGLEV trains
Magnetic levitation
Trains can be made to
‘float’ on strong
superconducting
magnets
Eliminate friction between train and track
29. MRI Scanner
Magnetic
Resonance Imaging
Used to determine
what is going on
inside a human body
Body exposed to
strong superconductor
derived magnetic field
Hydrogen atoms release energy at a
frequency that can be read by a computer
30. Electrical power line
Electrical cable made of
superconductors increase efficiency
Reduce loss of energy from heat
Battery + Bulb in a circuit- Electric field along wires
Battery + Bulb in a circuit- Electric field along wires
Battery + Bulb in a circuit- Electric field along wires
Potential difference, V=Work done, W / Charge, QOrEnergy, E/Charge, QSI unit Volt (V)
1 volt = 1 Joule per Coulomb
The potential difference between A and B in a circuit is 1 Volt if1 Joule of work is doneMoving 1 Coulomb of charge From A to B
VoltmeterMust always be connected in parallel
AmmeterMeasures current in AmperesConnected in series with a deviceLow resistance so little effect on the current flow
Higher potential difference, Higher Current Flow↑ V, ↑ I↓ V, ↓ IV ∝ I
Conductors that obey Ohm’s Law – OhmicConductors that don’t obey Ohm’s Law – Non-Ohmic
A measure of how much a conductor resists the flow of electricityGood conductor = low resistancePoor conductor = high resistance
V = IR V = potential differenceI = currentR = resistance
Resistance of a semiconductor decreases with temperature
A material whose resistance becomes zero when its temperature drops to a certain value called the critical temperature
Able to sustain large currents
Smaller power loss during transmission
Less heat energy wasted
Small sized motors and generators can be used
Magnetic levitationTrains can be made to ‘float’ on strong superconducting magnetsEliminates friction between train and track
Magnetic Resonance ImagingUsed to determine what is going on inside a human bodyBody exposed to strong superconductor derived magnetic fieldHydrogen atoms release energy at a frequency that can be read by a computer
Electrical cable made of superconductors increase efficiencyReduce loss of energy from heat