Positive rays consist of

Cathode rays are produced when the pressure is of the order of

$A$ metallic surface with a work function of $2 \, eV$,on heating to a temperature of $800 \, K$,gives an emission current of $1 \, mA$. If another metallic surface having the same surface area,same emission constant,but a work function of $4 \, eV$ is heated to a temperature of $1600 \, K$,then the emission current will be......$mA$.

Which scientist invented cathode rays?

In a discharge tube at $0.02\, mm$ pressure,there is a formation of
[$AIPMT$ $1996$]

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