Teacher's Guide for discussion about the nature, categories and characteristics of waves. For grade 7 lesson, quarter 3, module 2

1. GRADE 7
MODULE 2, QUARTER 3; LESSON 2.1
Teacher’s Guide for Discussion
MA. RACHEL B. ESPINO
Teacher, Science
Buhatan NHS, Sorsogon City

2. • WAVES are
perpendicular
disturbance that
moves away
from a source
and carries
energy with it.

3. 1. A wave is a travelling disturbance.
2. It carries energy from one phase to another.
3. Vibration causes wave motion
4. Waves travel through a medium

4. • According to the direction of movement of the
individual particles of the medium relative to
the direction that the waves travel.

5. • Waves in which particles of the medium move
in a direction perpendicular to the direction
that the wave moves.
• Particle motion is PERPENDICULAR to wave
motion.
Example: waves made by rope.

7. • Waves in which particles of the medium move
in a direction parallel to the direction that the
wave moves.
• Particle motion is PARALLEL to wave motion.
Example: sound wave

9. • Waves in which the particles of the medium
undergo a circular motion.
• In a surface wave, it is only the particles at the
surface of the medium that undergo the
circular motion. The motion of particles tend
to decrease as one proceeds further from the
surface.

11. • According to the waves’ ability to transmit
energy through a vacuum (empty space)

12. • A wave that is capable of transmitting energy
through a vacuum.
Example: rays of the sun, light

14. • Waves not capable to transmit energy through
a vacuum.
Example: sound

15. • The high points of waves are called CRESTS or
PEAKS while the low points are called
TROUGHS.

16. • The AMPLITUDE is the
maximum
displacement from the
rest position. It is the
height of the crest or
depth of a trough
measured from the
normal undisturbed
position.

17. • The WAVELENGTH, λ is
the distance between
two successive crests
or two successive
troughs. It is also equal
to the distance between
any two identical
points on successive
waves.

19. • The FREQUENCY, f is
the number of crests or
troughs that pass a
point per second. This
is equivalent to the
number of complete
waves generated per
second. Frequency is
measured in terms of
hertz (Hz).

20. • The PERIOD, T is the time taken to generate
one complete wave. It is also the time taken
for the crests or any given point on the wave
to move a distance of one wavelength
T = 1/f

21. • The SPEED, v of the wave is
the distance moved by a
wave in one second. Since
the wave crest travels a
distance of one wavelength
in one period, the wave
speed;
v = λ/T or
v = f λ