$A$ slit of width $a$ is illuminated by light of wavelength $\lambda$. The linear separation between $1^{st}$ and $3^{rd}$ minima in the diffraction pattern produced on a screen placed at a distance $D$ from the slit system is . . . . . . .

How will the diffraction pattern change when yellow light is replaced by blue light? The fringes will be

The phenomenon of diffraction was discovered by ...... .

$A$ parallel monochromatic beam of light is incident normally on a narrow slit. $A$ diffraction pattern is formed on a screen placed perpendicular to the direction of the incident beam. At the first maximum of the diffraction pattern,the phase difference between the rays coming from the edges of the slit is

$A$ slit of size $0.15 \,cm$ is placed at $2.1 \,m$ from a screen. On illuminating it by a light of wavelength $5 \times 10^{-5} \,cm$,the width of the central maxima will be:

For a light of wavelength $5000 \, \mathring{A}$ incident normally on a slit,the first diffraction minimum is formed at an angle of $\theta = 30^\circ$. The width of the slit is: