The angle of incidence at which reflected light is totally polarized for reflection from air to glass (refractive index $$n$$) is :

An electromagnetic wave of frequency $$v=3.0$$ $$MHz$$ passes from vacuum into a dielectric medium with permittivity $$ \in = 4.0.$$ Then

The maximum number of possible interference maxima for slit-separation equal to twice the wavelength in Young's double-slit experiment, is :

The work function of a substance is $$4.0$$ $$eV.$$ The longest wavelength of light that can cause photo-electron emission from this substance is approximately.