Light of frequency ${\rm{1}}{\rm{.5}}$ times the threshold frequency is incident on a photosensitive material. What will be the photoelectric current if the frequency is halved and intensity is doubled ?

$e/m$ ratio of anode rays produced in a discharge tube, depends on the

An oil drop with charge $q$ is held stationary between two plates with an external potential difference of 400 V. If the size of the drop is doubled without any change of charge, the potential difference required to keep the drop stationary will be

In Lenard's photoelectric experiment, which observation definitively proves the particle nature of light?

The {K_α}\;X-ray emission line of tungsten occurs at $\lambda = 0.021nm.$ The energy difference between $K$ and $L$ levels in this atom is about

When yellow light is incident on a surface, no electrons are emitted while green light can emit. If red light is incident on the surface, then

Which of the following is not the property of a cathode ray

In a photoelectric experiment, the incident light frequency is $3

u_0$, where$

u_0$is the threshold frequency. If the frequency is reduced to$1.5

u_0$ and the intensity is kept constant, how does the stopping potential change?

A parallel beam of light is incident normally on a plane surface absorbing 40% of the light and reflecting the rest. If the incident beam carries 60 W of power, the force exerted by it on the surface is

The collector plate in an experiment on photoelectric effect is kept vertically above the emitter plate. Light source is put on and a saturation photo current is recorded. An electric field is switched on which has a vertically downward direction

A metal surface is illuminated by a light of given intensity and frequency to cause photoemission. If the intensity of illumination is reduced to one-fourth of its original value, then the maximum kinetic energy of the emitted photoelectrons would become