Two sources $S_1$ and $S_2$ emit waves of wavelength $\lambda$. For destructive interference at point $P$,the path difference $(S_1P - S_2P)$ must be:

Light waves are emitted by a common source. For what time interval will the phase remain constant?

The wave nature of light is confirmed because:

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 $D$.

The intensities of two coherent light waves are $I$ and $4I$. The maximum intensity of the resultant wave after interference is: (in $I$)

The following figure shows sources $S_1$ and $S_2$ that emit light of wavelength $\lambda$ in all directions. The sources are exactly in phase and are separated by a distance equal to $1.5\lambda$. If we start at the indicated start point and travel along path $1$ and $2$,the interference produces a maxima all along: