An electron initially at rest, is accelerated through a potential difference of $ 200$ volt, so that it acquires a velocity $8.4 \times {10^6}m/s.$ The value of $e/m$ of electron will be
$2.76 \times {10^{12}}C/kg$
$1.76 \times {10^{11}}C/kg$
$0.76 \times {10^{12}}C/kg$
None of these
Which particles are responsible for conductivity of metals ?
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 $(c = 3 \times {10^8}m{s^{ - 1}})$
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)
When electron beam passes through an electric field, they gain kinetic energy. If the same beam passes through magnetic field, then
The ratio of momenta of an electron and an $\alpha - $particle which are accelerated from rest by a potential difference of $100 V$ is