A parallel beam of light of 500 nm falls on a narrow slit and the resulting diffraction pattern is observed on a screen 1 m away. It is observed that the first minimum is at a distance of 2.5 mm from the centre of the screen. Calculate the width of the slit.

Solution

Distance of nth minima from the centre of screen is given by, $straight a space equals space straight n space λD divided by straight d semicolon space$ a is the width of the slit.

For first minimum, n=1

So, width of the slit is given by,

$straight a space equals space fraction numerator 500 space straight x space 10 to the power of negative 9 end exponent cross times 1 over denominator 2.5 space cross times 10 to the power of negative 3 end exponent end fraction space straight m space space space space equals space 2 space cross times space 10 to the power of negative 4 end exponent space straight m$

Some More Questions From Wave Optics Chapter

Let us list some of the factors which could possibly influence the speed of wave propagation:
(i) nature of source.
(ii) direction of propagation.
(iii) motion of source and/or observer.
(iv) wave length.
(v) intensity of the wave.
On which of these factors, if any, does
(a) the speed of light in vacuum,
(b) the speed of light in a medium (say, the glass or water) depend?

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Wave Optics

A parallel beam of light of 500 nm falls on a narrow slit and the resulting diffraction pattern is observed on a screen 1 m away. It is observed that the first minimum is at a distance of 2.5 mm from the centre of the screen. Calculate the width of the slit.

Some More Questions From Wave Optics Chapter

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