The angle of minimum deviation produced by a thin prism in air is $\delta_1$. What will be the minimum deviation ($\delta_2$) if the prism is immersed in liquid ?
$\left[ {}^a n_g = \dfrac{3}{2}, \ {}^a n_\ell = \dfrac{1}{3} \right]$

In the phenomenon of refraction of light for the same angle of incidence

A double slit experiment is immersed in water of refractive index $1.33$. The slit separation is 1 mm, distance between slit and screen is $1.33$ m. The slits are illuminated by light of wavelength 6300 $\text{\AA}$. The fringe width is

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