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

The intensities of two waves are $2$ and $3$ units,respectively. The average intensity of light in the interference region will be ......

"If you illuminate two pinholes using two lamps, the interference pattern will not be observed" - Explain.

If two sources emit light waves of different amplitudes, then:

By a monochromatic wave,we mean

Two identical coherent sources are placed on a diameter of a circle of radius $R$ at a separation $x (x << R)$,symmetrically about the center of the circle. The sources emit waves of identical wavelength $\lambda$. Find the number of points on the circle with maximum intensity,given $x = 5 \lambda$.