Question

In a single-slit diffraction experiment, the width of the slit is made double the original width. How does this affect the size and intensity of the central diffraction band? Explain ?

Answer 1

In a single slit experiment the width of central maximum is given by ,

${\beta }_0=2D\lambda /d$

where $D=$ distance of screen from slit ,

$d=$ width of slit ,

$\lambda =$ wavelength of light used ,

now if width of slit is doubled $d^{\prime }=2d$

then, ${\beta }_0^{\prime }=2D\lambda /2d={\beta }_0/2$

size of central maximum will be halved .

Now, intensity of central maximum is independent of slit-width, therefore it will not be affected