In Millikan's experiment for the determination of the charge on the electron, the reason for using the oil is
It is a lubricant
Its density is higher
It vapourises easily
It does not vapourise
Which of the following have highest specific charge
An electron is accelerated through a potential difference of $200$ volts. If $e/m$ for the electron be $1.6 \times {10^{11}}$ $coulomb/kg$ , the velocity acquired by the electron will be
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
$n$ 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
The mass of the electron varies with