A proton is kept at rest. A positively charged particle is released from rest at a distance `d` in its field. Consider two experiments, one ini which the charged particle is also a proton and in another, a position. In the same time `t`, the work done on the two moving charged particles is

Options

A. Same as the same force law is involved in the two experiments
B. Less for the case of a positron, as the positron moves away more rapidly and the force on it weakens
C. More for the case of positron, as the positron moves away a larger distance
D. Same as the work done by charged particle on the stationary proton

Answer

C

Explanation

Force between two protons is same as that of between proton and a positron. As positron is much lighter than proton, it moves away through much larger distance compared to proton.
We know that, Work done = Force `xx` Distance. As forces are same in case of proton and positron but distance moved by positron is larger, hence, work done will be more.