The distance between a point source of light and a screen is $60 \ cm$. If this distance is increased to $180 \ cm$,what will be the intensity on the screen compared to the original intensity?

Two point sources separated by $d = 5\, \mu m$ emit light of wavelength $\lambda = 2\, \mu m$ in phase. $A$ circular wire of radius $R = 20\, \mu m$ is placed around the sources as shown in the figure. Determine the nature of interference at points $A, B, C,$ and $D$.

Two point sources $S_1$ and $S_2$ separated by a distance $10 \mu m$ emit light waves of wavelength $4 \mu m$ in phase. $A$ circular wire of radius $40 \mu m$ is placed around the sources as shown in the figure,where $O$ is the centre of the circle and $OS_1 = OS_2$. Determine the nature of the interference at points $A, B, C,$ and $D$.

Two coherent sources have different intensities. They produce an interference pattern. If the ratio of maximum to minimum intensities is $25:1$,find the ratio of the intensities of the sources.

Two waves having amplitudes in the ratio $5:1$ produce interference. The ratio of the maximum to minimum intensity is

$A$ 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 $\pi$)