Page 195 - text book form physics kssm 2020

Chapter 5
Waves
Figure 5.29 shows the wavefronts for plane waves and circular waves. Study the direction
of propagation and wavelength of these waves.

λ
λ • Direction of propagation of the wave is
perpendicular to the wavefront.
• Wavelength, λ is the same as the distance
between two consecutive wavefronts.

Plane wavefronts Circular wavefronts

Figure 5.29 Plane and circular wavefronts
What is the eff ect on the characteristics of waves when a wave is refl ected?

Activity 5.11

Aim: To study the refl ection of waves for plane waves
Apparatus: Ripple tank and its accessories, plane refl ector, digital xenon stroboscope, ruler
and protractor
Materials: Transparent plastic sheet, marker pen, cellophane tape and distilled water
Instructions:
1. Set up the apparatus as shown in Photograph 5.8.
2. Switch on the wave generator and adjust so that the frequency
t the frequency
of vibration is low.
ze
3. Adjust the frequency of the stroboscope to freeze
the movement of the waves.
4. Place the plane refl ector into the water tank.
5. Use a marker pen to mark on the plastic sheet
the position of:
(a) plane refl ector
(b) three consecutive incident wavefronts Transparent plasticra
T
(c) three consecutive refl ected wavefronts sheet attached tohe
s
g
6. Remove the plastic sheet and use a marker pen glass screenlas
to draw:
(a) shape of plane refl ector
(b) three incident wavefronts and refl ected Photograph 5.8
wavefronts
(c) direction of propagation of incident wave
and refl ected wave
(d) normal line
7. Determine the following values:
(a) angle of incidence, i and angle of refl ection, r
(b) incident wavelength and refl ected wavelength

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5.3.1
5.3.1 189