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

A charged particle is released from rest in a region of steady uniform electric and magnetic fields which are parallel to each other the particle will move in a

At a specific instant emission of radioactive compound is deflected in a magnetic field. The compound can emit

$(i)$ Electrons              $(ii)$ Protons                 $(iii)$ $H{e^{2 + }}$                  $(iv)$ Neutrons

The emission at the instant can be

${H^ + },\,H{e^ + }$ and ${O^{ + + }}$ ions having same kinetic energy pass through a region of space filled with uniform magnetic field $B$ directed perpendicular to the velocity of ions. The masses of the ions ${H^ + },\,H{e^ + }$and ${O^{ + + }}$ are respectively in the ratio $1:4:16$. As a result

Which of the following statement is true

Tesla is a unit for measuring