The unit of magnetic flux density (or magnetic induction) is:

An electron (mass $9 \times 10^{-31} \ kg$ and charge $1.6 \times 10^{-19} \ C$) moving with speed $v = c/100$ $(c = 3 \times 10^8 \ ms^{-1})$ is injected into a magnetic field $\vec{B}$ of magnitude $9 \times 10^{-4} \ T$ perpendicular to its direction of motion. We wish to apply a uniform electric field $\vec{E}$ together with the magnetic field so that the electron does not deflect from its path. Then:

Choose the correct statement.

Two protons move parallel to each other,keeping a distance $r$ between them,both moving with the same velocity $\vec{v}$. Then the ratio of the electric force to the magnetic force of interaction between them is:

$A$ circular coil connected to a battery of emf $E$ produces a certain magnetic induction field at its centre. The coil is unwound,stretched to double its length,rewound into a coil of $1/3$ of the original radius,and connected to a battery of emf $E^{\prime}$ to produce the same field at the centre. Then $E^{\prime}$ is

As the temperature of the hot junction increases, the thermo $e.m.f.$