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1.3 Refraction of waves

www.myfunphysicsworld.blogspot.com

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By the end of this lesson you should be able to…

• Describe refraction of waves in terms of the angle of incidence, angle of refraction, wavelength, frequency, speed and direction of propagation

• Draw a diagram to show refraction of waves.


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Refraction

• Occurs when there is a change of direction of the propagation of waves when it travel from a medium* to another medium due to a change in speed

• *Light & Sound: density

Water wave: depthwww.myfunphysicsworld.blogspot.com

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Refraction

The spoon looks bent when dipped in water

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REFRACTIONOF

LIGHT


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•Snell’s Law

•Refractive index, n = sin i / sin r


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REFRACTIONOF

WATER WAVE


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Case 1

i = 0o


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Deep to shallow

1. Angle of incidence, i = 0o, Angle of refraction, r = 0o, >>direction of propagation remain unchanged.

2. Wavelength decreases

3. Frequency unchanged

4. Velocity decreases

Deep region Shallow region


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Shallow to deep 1. Angle of incidence, i = 0o, Angle of refraction, r

= 0o, >>direction of propagation remain unchanged.

2. Wavelength increases3. Frequency unchanged4. Velocity increases

Shallow region Deep region


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Case 2i = 0o

5setia n amanah until here 7jan


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Deep to shallow 1. Angle of incidence, i = 0o,

direction : move toward the normal2. Wavelength decreases 4. Frequency unchanged3. Velocity decreases

Deep region Shallow region


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Deep regionShallow region

Shallow to deep 1. Angle of incidence, i = 0o, direction : move away from the normal2. Wavelength increases 3. Frequency unchanged4. Velocity increases


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a) What is the phenomenon observed when water waves pass through the shallow region

b) How does the direction of waves change when passing from the deep region to the shallow region?

c) When waves pass from the deep region to the shallow region, how do the following properties of the wave change?

i) directionii) wavelength

iii) speed iv) frequency

Shallow regionDeep region


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Homework


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Shallow deep shallow

1


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Deep shallow Deep

2


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Shallow deep shallow

1


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Deep shallow Deep

2


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Diagram 6.1 show the sideview of two ripple tanks. When the motors are switch on, water waves with same frequency are produced.

SPM 2009 P2A#6

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Diagram 6.2 shows the waves formed on the screens


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(a)What is the meaning of frequency? (1m)

(b)Observe diagram 6.1 and 6.2,(i) Compare the depth of water region in Region X and Y. (1m)

(ii) Compare the wavelength of water region in Region X and Y. (1m)

(iii) Relate the depth of water to the wavelength of the waves (1m)

(iv) Name the phenomenon involved (1m)


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• (c) Explain why the wavefront of sea water will follow the shape of the shore when it approaches the shore. (3m)

• Refracted

• Wavelength

• speed


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Documents

angle of refraction

direction of waves

shallow angle of incidence

change of direction

regionshallow regionshallow

propagation of waves

direction of propagationdraw

water waves