An electron with energy $0.1\,ke\,V$ moves at right angle to the earth's magnetic field of $1 \times 10^{-4}\,Wbm ^{-2}$. The frequency of revolution of the electron will be. (Take mass of electron $=9.0 \times 10^{-31}\,kg$ )

A particle moving in a magnetic field increases its velocity, then its radius of the circle

A current of $i$ ampere is flowing in an equilateral triangle of side $a$. The magnetic induction at the centroid will be

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 proton moving with a velocity, $2.5 \times {10^7}\,m/s$, enters a magnetic field of intensity $2.5\,T$ making an angle ${30^o}$ with the magnetic field. The force on the proton is

A charged particle enters a magnetic field $H$ with its initial velocity making an angle of $45^\circ $ with $H$. The path of the particle will be