The resultant amplitude in interference with two coherent sources depends upon:

In an interference experiment,the ratio of amplitudes of coherent waves is $\frac{a_1}{a_2} = \frac{1}{3}$. The ratio of maximum and minimum intensities of fringes will be

Light waves from two coherent sources arrive at two points on a screen with path difference of $0$ and $\frac{\lambda}{2}$. The ratio of intensities at the points is $(\cos 0^{\circ}=1, \cos \pi=-1)$.

Two light sources are said to be coherent if they are obtained from

Consider the following statements about interference of light:
$A$. The interference fringes are equally bright and equally spaced.
$B$. At the centre of a bright fringe,the intensity is four times the intensity of the incident wave.
$C$. For constructive interference of two waves,the crest of one wave coincides with the trough of another wave.
Which of the above statements are correct?

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,