Diffraction from a Single Slit

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Diffraction from a Single Slit

Waves diffract as they move through small gaps - that's the easy bit! But how can we calculate how much diffraction there will be, and what use is it to us anyway?

Calculating the angle of diffraction:


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We can calculate the position of the dark fringes using the formula above, where:

θ = angle from the centre to the minimum

n = order of the minimum

b = width of the slit (m)

λ = wavelength of wave being diffracted (m)

What can we use this for?

Diffraction is not only an issue with light waves, it also affects all the electromagnetic waves, water waves and sound waves, etc. This means that we have to take diffraction into account when designing equipment such as loud speakers and satellite dishes.

For example:

The size of a speaker will affect the amount of diffraction of the sound waves leaving it, and will therefore change the width of the central maxima of the diffraction pattern produced!


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