Question

It shows the light intensity on a viewing screen behind a circular aperture. What happens to the width of the central maximum if the

a. The wavelength of the light is increased.

b. The diameter of the aperture is increased.

c. How will the screen appear if the aperture diameter is less than the light wavelength?

Short answer

The central maximum breadth is

(a) The width gets larger.

b) The width reduces.

(c) Gray, almost continuously, with no minima.

Step-by-step solution

Light through an aperture

Waves spread out when they pass between apertures or around objects, which is known as diffraction. This occurs when the aperture or object has the same actual size as the incident wave's wavelength.

The light's wavelength and also the aperture's diameter

Hence, ${\theta }_1=\frac{1.22\lambda }{D}$we know.

The width increases as the height is increased.

The width decreases as the diameter is increased.

Aperture diameter

For diffraction to take place, the aperture size must be of the same order as the wavelength of light, hence almost uniformly gray with no minima.