The relation between current and charge is given by $I = A T^2 e^{qV / V_L}$. What is the value of $V_L$?

$A$ beam of cathode rays is subjected to crossed electric $(E)$ and magnetic fields $(B).$ The fields are adjusted such that the beam is not deflected. The specific charge of the cathode rays is given by (where $V$ is the potential difference between cathode and anode):

Explain the emission of electrons from a metal. Define work function. Write its unit,and state the factors upon which the work function of a metal depends.

The mass of a photoelectron is

Positive rays consist of

Which one of the following devices makes use of the electrons to strike certain substances to produce fluorescence?