Three particles having their charges in the ratio of $1 : 3 : 5$ produce the same spot on the screen in Thomson's experiment. Their masses are in the ratio of

$A$ cathode emits $1.8 \times 10^{14}$ electrons per second when heated. When $400 \ V$ is applied to the anode,all the emitted electrons reach the anode. The charge on an electron is $1.6 \times 10^{-19} \ C$. The maximum anode current is ............ $\mu A$.

For a thermionic emitter (metallic),if $J$ represents the current density and $T$ is its absolute temperature,then the correct curve between $\log_e \frac{J}{T^2}$ and $\frac{1}{T}$ is:

The minimum value of electric field required to pull out electrons from a metal is approximately . . . . . . $V$/cm.

Cathode rays and canal rays produced in a certain discharge tube are deflected in the same direction if

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.