In the phenomenon of electric discharge through gases at low pressure,the coloured glow in the tube appears as a result of
[$AIPMT$ $2008$]

$(a)$ 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?

Which one of the following is not electromagnetic in nature?

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

What is the speed of cathode rays?

The cathode rays have particle nature because of the fact that