Two protons move parallel to each other, keeping distance $r$ between them, both moving with same velocity $\vec V\,$. Then the ratio of the electric and magnetic force of interaction between them is
$c^2 / v^2$
$2c^2 / v^2$
$c^2 / 2v^2$
None
An electron enters with a velocity ${\rm{\vec v}},{{\rm{v}}_0}{\rm{\hat i}}$ into a cubical region (faces parallel to coordinate planes) in which there are uniform electric and magnetic fields. The orbit of the electron is found to spiral down inside the cube in plane parallel to the $\mathrm{xy}$ - plane. Suggest a configuration of fields $\mathrm{E}$ and $\mathrm{B}$ that can lead to it.
A charge $Q$ moves parallel to a very long straight wire carrying a current $l$ as shown. The force on the charge is
An electron moves with a speed of $2 \times 10^5\, m/s$ along the $+ x$ direction in a magnetic field $\vec B = \left( {\hat i - 4\hat j - 3\hat k} \right)\,tesla$. The magnitude of the force (in newton) experienced by the electron is (the charge on electron $= 1.6 \times 10^{-19}\, C$)
An electron is moving along the positive $X$$-$axis. You want to apply a magnetic field for a short time so that the electron may reverse its direction and move parallel to the negative $X$$-$axis. This can be done by applying the magnetic field along
The dimension of the magnetic field intensity $B$ is