Energy of electrons can be increased by allowing them
To fall through electric potential
To move in high magnetic field
To fall from great heights
To pass through lead blocks
In Bainbridge mass spectrograph a potential difference of $1000 V$ is applied between two plates distant $1$ cm apart and magnetic field in $B = 1T$. The velocity of undeflected positive ions in m/s from the velocity selector is
Which particles are responsible for conductivity of metals ?
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
The specific charge of an electron is
In a Thomson set-up for the determination of e/m, electrons accelerated by $2.5$ $kV$ enter the region of crossed electric and magnetic fields of strengths $3.6 \times {10^4}V{m^{ - 1}}$ and $1.2 \times {10^{ - 3}}T$ respectively and go through undeflected. The measured value of $e/m$ of the electron is equal to