Waves and diffraction refraction reflection diffraction questions

Diffraction previous next

D T N A F F R O C I I 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. D T N A F F R O C I I previous next

Diffraction of water waves previous next

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spreading (diffraction) Small amount of spreading (diffraction) The wavelength of the waves is much smaller than the size of the gap previous next

spreading (diffraction) The wavelength is the same size as the gap so there is very good spreading (diffraction) previous next

Diffraction of sound waves Speed of sound in air = 330m/s Typical frequency = 440Hertz Work out the wavelength of these sound waves Speed = wavelength x frequency Wavelength = speed/frequency Wavelength = 330/440 = 0.75metres About the same size as the width of a door previous next

Diffraction of light waves previous next

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 previous next

Long wavelengths diffract more than short wavelengths. 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. previous next

Diffraction of radio waves previous next

This transmitter is producing radio waves previous next

Will the people living here be more likely to receive This house is in the shadow of some hills The aerial is on a pole to try and improve the reception of radio waves. Will the people living here be more likely to receive long wave or short wave radio programmes? previous next

Short radio waves are hardly diffracted over the top of the hill. Short wave radio signals do not reach the aerial previous next

Long wavelength radio waves can be diffracted over the top of the hill. The hill acts rather like an edge causing diffraction Long wavelength radio waves are received by the aerial previous next

Top View There is very little diffraction of short wavelength radio waves when they pass between two hills Top View previous next

Long wave radio waves are more likely to have wavelengths 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. Top View Long wave radio waves are more likely to have wavelengths which are similar to the size of the gap between the hills. previous next