In $$\mathrm{P}^{\text {th }}$$ second, a particle describes angular displacement of '$$\beta$$' rad. If it starts from rest, the angular acceleration is

Inductance per unit length near the middle of a long solenoid is $$\left(\mu_0=\right.$$ permeability of free space, $$\mathrm{n}=$$ number of turns per unit length, $$\mathrm{d}=$$ the diameter of the solenoid)

One of the slits in Young's double slit experiment is covered with a transparent sheet of thickness $$2.9 \times 10^{-3} \mathrm{~cm}$$. The central fringe shifts to a position originally occupied by the $$25^{\text {th }}$$ bright fringe. If $$\lambda=5800$$ $$\mathop A\limits^o $$, the refractive index of the sheet is