Which of the following phenomena support the wave theory of light?
$(1)$ Scattering
$(2)$ Interference
$(3)$ Diffraction
$(4)$ Velocity of light in a denser medium is less than the velocity of light in a rarer medium

The difference in the number of wavelengths, when yellow light propagates through air and vacuum columns of the same thickness, is one. Find the thickness of the air column. Given: Refractive index of air $\mu_a = 1.0003$, Wavelength of yellow light in vacuum $\lambda_0 = 6000 \text{ Å}$.

$A$ zone plate of focal length $60\,cm$ behaves as a convex lens. If the wavelength of incident light is $6000\,\mathring{A},$ then the radius of the first half-period zone will be:

According to the corpuscular theory of light,which of the following phenomena can be explained?

Fraunhofer lines are produced by the absorption of light in

The intensity of light from a continuously emitting laser source operating at $638 \,nm$ wavelength is modulated at $1 \,GHz$. The modulation is done by momentarily cutting the intensity off with a frequency of $1 \,GHz$. What is the farthest distance apart two detectors can be placed in the line of the laser light,so that they can see the portions of the same pulse simultaneously?
(Consider the speed of light in air $c = 3 \times 10^{8} \,m/s$)