question_answer

A charged particle enters a uniform magnetic field with a certain speed at right angles to it. In the magnetic field a change could occur in its

A)  kinetic energy

B)  angular momentum

C)  linear momentum

D)  speed

Correct Answer: C

Solution :

Force acting on particle due to magnetic field B is \[F=q\,\,\vec{v}\,\,\times \,\,\vec{B}\] ?..(i) and centripetal force is \[F=\frac{m{{v}^{2}}}{r}\] ?..(ii) From Eqs. (i) and (ii), we get \[B=\frac{mv}{rq}=\frac{linear\text{ }momentum}{charge}\]