The mass of a particle is $400$ times than that of an electron and the charge is double. The particle is accelerated by $5 V$. Initially the particle remained in rest, then its final kinetic energy will be ……….. $eV$

In Millikan’s oil drop experiment, an oil drop of mass $16 \times {10^{ – 6}}kg$ is balanced by an electric field of ${10^6}V/m.$ The charge in coulomb on the drop, assuming $g = 10\,m/{s^2}$ is

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)

$n$ Millikan oil drop experiment, a charged drop of mass $1.8 \times {10^{ – 14}}kg $ is stationary between its plates. The distance between its plates is $0.90 cm$ and potential difference is $2.0$ kilo volts. The number of electrons on the drop is

In Millikan's experiment for the determination of the charge on the electron, the reason for using the oil is