$\mathrm{L}=2 \mathrm{H}, \mathrm{C}=5 \mathrm{mF}$ and $\mathrm{R}=12 \Omega$ are connected in series to an a.c. generator of frequency 50 Hz . Then

An electron of stationary Hydrogen atom passes from fifth energy level to ground level. The velocity that the atom acquired as a result of photo emission is

( $\mathrm{m}=$ mass of electron, $\mathrm{R}=$ Rydberg's constant)

( $\mathrm{h}=$ Planck's constant)

A diffraction pattern is obtained using a beam of red light. If red light is replaced by blue light then

The magnetic energy in an inductor changes from maximum value to minimum value in 5 ms . When connected to an a.c. source, the frequency of the source is