$A$ wavefront presents one,two and three $HPZ$ at points $A, B$ and $C$ respectively. If the ratio of consecutive amplitudes of $HPZ$ is $4 : 3$,then the ratio of resultant intensities at these points will be

In a single slit diffraction experiment, a parallel beam of green light of wavelength $\lambda = 550 \,nm$ passes through a slit of width $a = 0.20 \,mm$. The transmitted light is collected on a screen at a distance $D = 100 \,cm$ away. The distance of the first-order minima from the central maximum is $x \times 10^{-5} \,m$. The value of $x$ is:

"The person standing behind the open door inside the room can hear the voice of the person standing on the other side of the door but they cannot see each other". Give an experiment based on the diffraction for this statement.

$A$ circular disc is placed in front of a narrow source. When the point of observation is $2 \, m$ from the disc,it covers the first $HPZ$. The intensity at this point is $I$. When the point of observation is $25 \, cm$ from the disc,the intensity will be:

Light of wavelength $\lambda$ is incident on a single slit of width $a$ and the distance between the slit and the screen is $D$. In the diffraction pattern, if the slit width is equal to the width of the central maximum, then $D$ is equal to:

The angular spread of the central maximum in a diffraction pattern does not depend on . . . . . . .