Question

A proton, a deuteron and an $\alpha$-particle accelerated through the same potential difference enter a region of uniform magnetic field, moving at right angles to $B$. What is the ratio of their kinetic energies?

• A. $2:1:1$
• B. $2:2:1$
• C. $1:2:1$
• D. $1:1:2$

Answer 1

The correct option is D $1:1:2$

Kinetic energy gained by charged particle of charge $q$ when accelerated under a potential difference $V$ will be $KE=qV$
For a given $V,KE\propto q$
For proton, deuteron and $\alpha$-particle the ratio of charges is $1:1:2$