A resistor of 100 $\Omega$, inductor of self inductance $\left(\dfrac{4}{\pi^2}\right)$ H and a capacitor of unknown capacity are connected in series to an a.c. source of 200 V and 50 Hz. When the current and voltage are in phase, the value of capacity is

If a parallel beam of light is incident on spherical mirrors then after reflection they pass through focal point. If F is the focal length and R is the radius of curvature of mirror then

Choose the correct statement from the following.
Brewster's angle for a transparent medium is

In Young's double slit experiment, the angular width of a fringe is found to be $0.2^\circ$ on a screen placed 1m away. The wavelength of light used in 600 nm. If the entire apparatus is immersed in water of refractive index 4/3. the angular width of the fringe will be