In the circuit shown below, the ac source has voltage $V = 30 \cos(\omega t)$ volt with $\omega = 2000$ rad/s. What will be the amplitude of the current?

For large magnifying power of a telescope

A ray of light is incident of the surface of a glass plate at an angle of incidence equal to Brewster's angle $\Phi$. If $\mu$ denotes the refractive index of glass w.r.t. air, then what will be the angle between reflected and refracted rays?

Two polaroid A and B placed in such a way that the pass-axis of polaroid are perpendicular to each other. Now, another polaroid C is placed between A and B bisecting angle between them. If intensity of unpolarised light is $I_0$ then intensity of transmitted light after passing through polaroid B will be