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

Which of the following is the path difference for destructive interference?

The path difference between two interference waves at a point on a screen is $11.5 \lambda$. The point is

Four monochromatic and coherent sources of light,emitting waves in phase of wavelength $\lambda$,are placed at the points $x = 0, d, 2d$,and $3d$ on the $x$-axis. The intensity of the waves reaching a point $P$ far away on the $+x$ axis from each of the four sources is almost the same,and equal to $I_0$. Then,

When a light wave undergoes reflection at the interface from air to glass,the change in phase of the reflected wave is equal to

$A$ beam with wavelength $\lambda$ falls on a stack of partially reflecting planes with separation $d$. The angle $\theta$ that the beam should make with the planes so that the beams reflected from successive planes may interfere constructively is (where $n = 1, 2, \dots$)