A beam of cathode rays is subjected to crossed electric $(E)$ and magnetic fields $(B).$ The fields are adjusted such that the beam is not deflected. The specific charge of the cathode rays is given by (where $V$ potential diffrence between kethod and anode)

A stick of $1 \,m$ is moving with velocity of $2.7 \times {10^8}m{s^{ – 1}}$. ……….. $m$ is the apparent length of the stick  $(c = 3 \times {10^8}m{s^{ – 1}})$

Energy of electrons can be increased by allowing them

In a parabola spectrograph, the velocities of four positive ions $P,Q,R$ and $S$ are $v_1$, $v_2$, $v_3$ and $v_4$ respectively

In Milikan’s experiment, an oil drop having charge $q$ gets stationary on applying a potential difference $V$ in between two plates separated by a distance $‘d’$. The weight of the drop is