Cathode rays are

The mass of the electron varies with

Which of the following has the highest specific charge?

$A$ 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):

To emit an electron from a metal surface, the minimum electric field required is . . . . . . .

The mass of a photoelectron is