The thermionic emission of electrons is due to:

What is specific charge? Write its standard value.

How can the mass of an electron be obtained?

$A$ 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......$mA$.

Thermions are

Write the name of the universal and fundamental particle of matter.