Which property of light is responsible for interference?

The frequency of a light wave with a wavelength of $500 \, \mathring A$ is $....... \, Hz$.

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

If $\frac{\text{Path difference}}{\text{Wave length}} = n$ (where $n$ is an integer),what kind of interference is formed?

Light waves producing interference have their amplitudes in the ratio $3: 2$. The intensity ratio of maximum and minimum of interference fringes is

Two coherent sources separated by a distance $d$ are radiating in phase with a wavelength $\lambda$. $A$ detector moves in a large circle around the two sources in the plane of the two sources. The angular position of the $n = 4$ interference maxima is given as