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 waves of intensities $I_0$ and $9I_0$ superpose at a point to produce a resultant intensity of $7I_0$. Calculate the phase difference between the light waves.

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

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 monochromatic light beams of intensity $16$ and $9$ units are interfering. The ratio of intensities of bright and dark parts of the resultant pattern is

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