The correct formula for fringe visibility is

The colour of light is characterised by which of the following characteristics?

Two coherent plane light waves of equal amplitude make a small angle $\alpha (\alpha \ll 1)$ with each other. They fall almost normally on a screen. If $\lambda$ is the wavelength of the light waves,the fringe width $\Delta x$ of the interference pattern of the two sets of waves on the screen is:

Two plane polarized light waves combine at a certain point whose electric field components are $E_1 = E_0 \sin(\omega t)$ and $E_2 = E_0 \sin(\omega t + \frac{\pi}{3})$. Find the amplitude of the resultant wave.

The interference pattern is obtained with two coherent light sources of intensity ratio $n$. In the interference pattern,the ratio $\frac{I_{max} - I_{min}}{I_{max} + I_{min}}$ will be

If the wavelength of light is $4000 \, Å$, then the number of waves in a length of $1 \, mm$ will be: