The fact that electric charges are integral multiples of the fundamental electronic charge was proved experimentally by

In Thomson spectrograph experiment, four positive ions $P,Q,R$ and $S$ are situated on $Y-X$ curve a shown in the figure

Which of the following will have the least value of $\frac{q}{m}$

The mass of the electron varies with

The ratio of specific charge of an $\alpha $ -particle to that of a proton is

Cathode rays enter into a uniform magnetic field perpendicular to the direction of the field. In the magnetic field their path will be