In cathode ray oscillograph, the focusing of beam on the screen is achieved by

Which is not true with respect to the cathode rays

The light rays having photons of energy $1.8\;eV$ are falling on a metal surface having a work function $1.2\;eV.$ What is the stopping potential to be applied to stop the emitting electrons

An ionisation chamber, with parallel conducting plates as anode and cathodes has $5 imes {10^7}{\rm{\;c}}{{\rm{m}}^{ - 3}}$ electrons and the same number of singly charged positive ions per ${\rm{c}}{{\rm{m}}^3}$. The electrons are moving toward the anode with velocity 0.4${\rm{m}}{{\rm{s}}^{ - 1}}$. The current density from anode to cathode is $4{\rm{\mu A}}{{\rm{m}}^{ - 2}}.$ The velocity of positive ions moving towards cathode is

The ratio of specific charge of an $\alpha$-particle to that of a proton is

A metal surface with work function $\phi$ is illuminated by monochromatic light of frequency $

u$. If the stopping potential is$V_0$, and the mass of an electron is$m$, the maximum speed of the emitted photoelectrons is:

Which of the following event, support the quantum nature of light?

The temperature at which protons in proton gas would have enough energy to overcome Coulomb barrier of $4.14 imes {10^{ - 14}}$ J is (Boltzmann constant

=1.38$imes {10^{ - 23}}\;{\rm{J}}{{\rm{K}}^{ - 1}}){\rm{\;}}$

A photo-sensitive material would emit electrons, if excited by photons beyond a threshold. To overcome the threshold, one would increase the

Light of frequency $1.5$ times the threshold frequency is incident on a photosensitive material. If the frequency is halved and intensity is doubled, what will be the photoelectric current?

The curve drawn between velocity and frequency of photon in vacuum will be a