$A$ slit of width $d$ is illuminated by white light. The first minimum for red light $(\lambda = 6500\,\mathring{A})$ will fall at $\theta = 30^\circ$ when $d$ will be

In a single slit diffraction pattern,a light of wavelength $6000 \mathring A$ is used. The distance between the first and third minima in the diffraction pattern is found to be $3 \text{ mm}$ when the screen is placed $50 \text{ cm}$ away from the slit. The width of the slit is . . . . . . $\times 10^{-4} \text{ m}$.

In a Fraunhofer diffraction at a single slit of width $d$ and incident light of wavelength $5500 \text{ Å}$,the first minimum is observed at an angle $30^{\circ}$. The first secondary maxima are observed at an angle $\theta=$

Describe the simplest experiments to observe a diffraction pattern.

Two wavelengths $590 \ nm$ and $596 \ nm$ of sodium light are used one after another to study the diffraction taking place at a single slit of aperture $2.4 \ mm$. The distance between the slit and the screen is $2 \ m$. The separation between the positions of the first secondary maximum of the diffraction pattern obtained in the two cases is:

$A$ screen is placed $0.5 \,m$ away from a single slit which is illuminated by a monochromatic light of wavelength $6000 \text{ Å}$. If the distance between the first and third minima in the diffraction pattern on the screen is $3 \,mm$, then the slit width is: (in $\,mm$)