Two ions have equal masses but one is singly ionized and second is doubly ionized. They are projected from the same place in a uniform transverse magnetic field with same velocity then:
$(a)$ Both ions will go along circles of equal radii
$(b)$ The radius of circle described by the single ionized charge is double of radius of circle described by doubly ionized charge
$(c)$ Both circle do not touches to each other
$(d)$ Both circle touches to each other

Two electrons are moving along parallel lines unidirectionarly with same velocity they will

A proton enters a magnetic field of flux density $1.5\,weber/{m^2}$ with a velocity of $2 \times {10^7}\,m/\sec $ at an angle of $30^\circ $ with the field. The force on the proton will be

If an electron enters a magnetic field with its velocity pointing in the same direction as the magnetic field, then

Proton, deuteron and alpha particle of same kinetic energy are moving in circular trajectories in a constant magnetic field. The radii of proton, deuteron and alpha particle are respectively $r_p, r_d$ and $r_{\alpha}$ Which one of the following relation is correct?

An electron enters a region where electrostatic field is $20\,N/C$ and magnetic field is $5\,T$. If electron passes undeflected through the region, then velocity of electron will be.....$m{s^{ - 1}}$