Page 196 - text book form physics kssm 2020

Discussion:
1. Compare angle of incidence and angle of refl ection.
2. Compare incident wavelength and refl ected wavelength.
3. Can the stroboscope freeze the movement of incident waves and refl ected waves at the
same time?
4. Based on your answer in question 3, compare the frequency of incident wave and
frequency of refl ected wave.
5. From your answers in questions 2 and 4, compare the speed of incident wave with
refl ected wave.

Photograph 5.9 shows refl ected plane water waves in a ripple tank. Th e phenomenon of
refl ected waves only cause the wave direction to change while other characteristics of the wave
do not change.

Plane reflector

λ λ Normal
1 1

i i
r r Reflected wavefronts

Incident wavefronts
λ λ
2 2

Photograph 5.9 Refl ection of plane water waves by a plane refl ector
Table 5.2 summarizes the eff ects of refl ection on the characteristics of waves.

Table 5.2 Eff ects of refl ection on characteristics of waves

Characteristic of wave Eff ect aft er refl ection of wave
Angle of incidence and angle of refl ection Angle of incidence = angle of refl ection
Wavelength No change

Frequency No change

Wave speed No change
Direction of propagation Changes with the condition that the angle of incidence
is the same as angle of refl ection

190
190 5.3.1
190
190
5.3.1