Question

Identify which of the following color light, when passed through a double-slit opening, will produce the widest central band of light on the screen?

• A. red
• B. orange
• C. yellow
• D. green
• E. blue

Answer 1

The correct option is A red

Fringe width $\beta =\frac{\lambda D}{d}$ where $\lambda$ is the wavelength of the light used

$⟹$ $\beta \propto \lambda$

As wavelength of the red light is the largest among the visible light, thus fringe width is the greatest formed due to red light.