Find the half-angular width of the central maximum in the Fraunhofer diffraction pattern produced by a slit of width $12 \times 10^{-5} \text{ cm}$,when illuminated by monochromatic light of wavelength $6000 \, \mathring{A}$. (Answer in degrees)

$A$ converging lens of a telescope with a diameter of $5 \text{ cm}$ has a focal length of $25 \text{ cm}$. In the focal plane of the lens, the distance between the centres of the Fraunhofer diffraction pattern is (wavelength of light used = $5000 \text{ Å}$, Rayleigh's criterion is satisfied).

What do the Fraunhofer lines in the solar spectrum indicate?

In a Fraunhofer diffraction experiment at a single slit using light of wavelength $400 \ nm$,the first minimum is formed at an angle of $30^{\circ}$. The direction $\theta'$ of the first secondary maximum is given by

Fresnel diffraction is produced due to light rays falling on a small obstacle. The intensity of light at a point on a screen beyond an obstacle depends on

$A$ student is jogging on a straight path with a speed of $5.4 \,km/h$. Perpendicular to the path is a pipe with its opening $8 \,m$ from the road (see figure). The diameter of the pipe is $0.45 \,m$. At the other end of the pipe is a speaker emitting sound of $1280 \,Hz$ towards the opening of the pipe. As the student passes in front of the pipe,she hears the speaker sound for $T$ seconds. $T$ is in the range (Take speed of sound $= 320 \,m/s$):