A photon beam of energy 12.1eV is incident on a hydrogen atom. The orbit to which electron of H-atom be excited is

Unpolarized light is incident on a plane glass surface having refractive index . The angle of incidence at which reflected and refracted rays would become perpendicular to each other is:

Photoelectric emission from a given surface of metal can take place when the value of a ‘physical quantity’ is less than the energy of incident photon. The physical quantity is:

Horizontal and vertical components of earth’s magnetic field at a place are equal. The angle of dip at that place is ___ .

OR

A free floating magnetic needle at North Pole is____ to the surface of earth.

The magnetic flux linked with a coil changes by 2×10^-2Wb when the current changes by 0.01A. The self inductance of the coil is_ .