Multiple Choice QuestionsThe threshold frequency for a metallic surface corresponds to an energy of 6.2 eV, and the stopping potential for a radiation incident on this surface 5 V. The incident radiation lies in
X-ray region
ultra-violet region
infra-red region
infra-red region
An electromagnetic wave in vaccum has the electric and magnetic fields 
and 
which are always perpendicular to each other. the direction of polarisation is given by 
and that of wave propagation by 
then
During the propagation of electromagnetic waves in a medium:
Electric energy density is equal to the magnetic energy density.
Both electric and magnetic energy densities are zero.
Electric energy density is double of the magnetic energy density.
Electric energy density is double of the magnetic energy density.
