Cathode rays are

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

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

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

$(a)$ Estimate the speed with which electrons emitted from a heated emitter of an evacuated tube impinge on the collector maintained at a potential difference of $500\;V$ with respect to the emitter. Ignore the small initial speeds of the electrons. The specific charge of the electron,$i.e.$,the $e/m$ is given to be $1.76 \times 10^{11}\; C\; kg^{-1}$.
$(b)$ Use the same formula you employ in $(a)$ to obtain electron speed for a collector potential of $10\;MV$. Do you see what is wrong? In what way is the formula to be modified?

Write observations of various experiments which suggest that cathode rays are a stream of negatively charged particles.