Two identical light sources $S_1$ and $S_2$ emit light of same wavelength $\lambda$. These light rays will exhibit interference if

The path difference between two interfering waves at a point on the screen is $171.5$ times the wavelength. If the path difference is $0.01029 \, cm$,find the wavelength in $\mathring{A}$.

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 coherent sources of light interfere and produce a fringe pattern on a screen. For the central maximum,the phase difference between the two waves will be,

Two monochromatic and coherent point sources of light are placed at a certain distance from each other in the horizontal plane. The locus of all those points in the horizontal plane which have constructive interference will be

Two coherent sources of intensities $I$ and $4I$ interfere. The maximum and minimum intensities of the resultant wave are: