What is the speed of cathode rays?

The ratio of thermionic currents $(I/I_0)$ for a metal when the temperature is slowly increased from $T_0$ to $T$ is shown in the figure. ($I$ and $I_0$ are currents at $T$ and $T_0$ respectively). Which curve correctly represents this relationship?

The thermionic emission of electrons is due to:

Which scientist invented cathode rays?

An electron is:

In Thomson's method of determining $e/m$ of electrons,how are the electric and magnetic fields arranged relative to the electron beam?