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1.2 ANALYSING REFLECTION OF WAVES
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Light
Convex water surface
Light is converged (refracted)
Bright
Concave water surface
Light is diverged (refracted)
Dim
Waterfronts
(crest)
Ripple tank
Water
Screen
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1.2 ANALYSING REFLECTION OF WAVES
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Reflection of waves• Occurs when a wave strikes an obstacle.
• The phenomenon obeys the Laws of Reflections.
i) the angle of incidence = the angle of reflection
ii) the incidence wave , the reflected wave and the normal lie in the same plane.
• the incidence wave = wave before reflection
1. Reflection (plane wave) by plane reflector
Plane reflect
or
Vibrator
Sponge
Motor
Water
Ripple tank
Compare the wave characteristics before and after reflection
Aspects:
• Wavelength/frequency
• Wavefront shape
• Direction
• The angle
• Velocity
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Comparison Wave Reflection
Aspects Before & after reflection
Wavelength Same
Frequency Same
Speed Same
Direction changed
Wave front shape same
Velocity changed
How to draw the wavefront which reflected by plane reflector
1. Draw the direction of the incident waves
2. Draw the NORMAL line
3. Draw the direction of reflection waves. Make sure the angle i = r
4. Draw the wavefront of reflection waves that perpendicular to it direction
i r i r
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2. Reflection (plane wave) by convex reflector
Convex
reflector
Compare the wave characteristics before and after reflection
Aspects:
• Wavelength/frequency
• Wavefront shape
• Direction
• VelocityNext
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Concave
reflector
How to drawing the wavefront which reflected by concave reflector
?Guide
1. Draw the direction of incident wave
2. Draw the NORMAL
3. Draw the direction of the reflection waves. Make sure the angle i = r
4. Draw the wavefront of reflection waves that perpendicular to it the direction
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3. Reflection (circle wave) by plane surface
Compare the wave characteristics before and after reflection
Reflect
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Guide
Note
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Questions
