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Wave Boundaries

• Waves are absorbed ,transmitted and reflected at boundaries
• 1)Absorbed by second material-wave transfers energy to the material's energy stores. Often transferred to a thermal store leads to heating(how a microwave works)
• 2)Transmitted through second material-carries on travelling through new material. Often leads to refraction, can be used in communications as well as lenses of glasses and cameras
• 3)Reflected- incoming ray is neither absorbed or transmitted but 'sent back' away from second material. How echoes are created.

Refraction-Waves changing direction

• 1)Waves travel at different speeds with different densities. When a wave crosses a boundary between materials it changes speed.
• 2)If the wave hits the boundary at an angle , this changes the speed causes a change in direction
• 3)If the wave is travelling along the normal it will change speed but its not refracted
• 4)the greater the change in speed the more a wave bends( changes direction)
• 5)The waves bends towards the normal if it slows down, and away from the normal if it speeds up
• 6)Electromagnetic waves like light usually travel more slowly in denser materials.
• 7)How much an EM wave refracts can be affected by its wavelength -shorter wavelengths bend more, can lead to the wavelengths spreading out
• 8)Frequency of a wave stays the same when it crosses a boundary, this means that the change in speed is caused by a change in wavelength-the wavelength decreases if the wave slows down and increases if it speeds up.

Sound

• Sound travels as a wave
• 1)sound waves are caused by vibrating objectsyhmm,-
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