REFRACTIONTOPIC 14 : LIGHT

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WAVE BEHAVIOURAs a transverse wave light behave in the following

ways:

Reflected Refracted Diffracted

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REFRACTION OF LIGHT

The change in the direction of the light wave as they move from one medium to another.

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REFRACTION OF WAVESDue to the change in the speed of light as its passes

through substances of different optical density.

SubstanceA

SubstanceB P

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REFRACTION OF WAVESDue to the change in the speed of light as its passes

through substances of different optical density.

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Depends on the angle at which light hits the boundary between the different substances.

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April 2000 Waves - 9 Physics@Xinmin

Questions:1. Identify the shallow and deep water as shown on this photo of waves taken from a

ripple tank.

2. The following diagrams show three wavefronts passing from shallow water intodeep water. Complete the diagram to show the direction of the wavefronts aftercrossing the boundary.

3. a) On the diagram below show the direction of the wavefront as it passes over the

boundary XY.

b) Is the wave passing into deeper or shallower water?

CONSTRUCTION OF REFRACTED WAVES

April 2000 Waves - 9 Physics@Xinmin

Questions:1. Identify the shallow and deep water as shown on this photo of waves taken from a

ripple tank.

2. The following diagrams show three wavefronts passing from shallow water intodeep water. Complete the diagram to show the direction of the wavefronts aftercrossing the boundary.

3. a) On the diagram below show the direction of the wavefront as it passes over the

boundary XY.

b) Is the wave passing into deeper or shallower water?

Light passing through straight on.

Scenario A Scenario B

Light passing through at an angle. P

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REFRACTION OF LIGHT

Wavelength increases.

Speed increases.

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mLight rays will be affected as follows when moving from optically dense to optically less dense medium along the normal.

Light path is not refracted.

Wavelength decreases.

Speed decreases.

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REFRACTION OF LIGHTLight rays will be affected as follows when moving

from optically less dense to optically dense medium.

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The speed decreases.

\\\

The wavelength decreases.

Wave path is refracted towards the normal.

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REFRACTION OF LIGHT

The wavelength increases.

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mLight rays will be affected as follows when moving from optically dense to optically less dense medium.

Wave path is refracted away from the normal.

The speed increases.

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TERMINOLOGIES

Incident Angle

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Angle of Refraction

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LAWS OF REFRACTION

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REFRACTIVE INDEXFor light rays moving from a vacuum into a given

medium.

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REFRACTIVE INDEXRefractive index of some common materials.

Substances with high refractive index tend to refract light rays more.

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REFRACTION OF LIGHTOptical Illusion of Height and Depth

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Apparent position of objects in water14

REFRACTION OF LIGHTOptical Illusion of Height and Depth

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Apparent star position Mirages

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REFRACTION OF LIGHT

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Refractive index can also be determined as follows:

Apparent DepthReal Depth

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Light rays entering from the flat side.

Light rays entering from the curved side.

REFRACTION IN A SEMI CIRCULAR BLOCK

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REFRACTION IN TRIANGULAR BLOCK

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SUMMARY OF WAVE BEHAVIOUR

WavelengthSpeed

REFLECTION REFRACTION

WavelengthSpeed

Direction

Angle of Incidence

Angle of Reflection=

INCREASE / DECREASE

CONSTANT

TOWARDS / AWAY FROM NORMAL

DEPENDS ON OPTICAL DENISTY OF MEDIUM

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