Two beams of light having intensities $I$ and $4I$ interfere to produce fringes on a screen. The phase difference between the beams at point $A$ is $\pi/2$ and at point $B$ is $2\pi$. Find the resultant intensities at points $A$ and $B$.

Two waves of same intensity $I_0$ emitted from two sources having same phase difference $(\phi)$. Due to superposition of two waves,the intensity of resultant wave is directly proportional to . . . . . . .

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

Path difference between two light waves at a point $P$ for constructive interference will be

For a distinct interference pattern,the condition is that the ratio of intensities of light produced by both sources must be .....

$A$ and $B$ are two interfering sources where $A$ is ahead in phase by $54^{\circ}$ relative to $B$. The observation is taken from point $P$ such that $PB-PA=2.5 \lambda$. Then the phase difference between the waves from $A$ and $B$ reaching point $P$ is (in rad) (in $\pi$)