3. •Diffraction is the spreading
out of waves at edges and gaps.
•All types of waves can be diffracted.
•The amount of diffraction is
affected by the size of the
gap and the wavelength.
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7. Small amount of
spreading (diffraction)
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The wavelength of the
waves is much smaller
than the size of the gap
8. The wavelength is the
same size as the gap
so there is very good
spreading (diffraction)
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9. Typical frequency = 440Hertz
Speed of sound in air = 330m/s
Speed = wavelength x frequency
Work out the wavelength of these sound waves
Wavelength = speed/frequency
Wavelength = 330/440 = 0.75metres
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About the same size as the width of a door
11. To get spreading (diffraction) of the light
the gap it passes through has to be very
small-because the wavelength of light is
very small
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12. For edges
Long wavelengths diffract more than short
wavelengths.
For gaps
The wavelength should be the same size
as the gap to get good diffraction.
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18. There is very little diffraction of short wavelength
radio waves when they pass between two hills
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19. Long wavelength radio waves are more likely to be
diffracted when they pass between hills and are
more likely to be detected by the aerial.
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