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 in which the charged particle is abo a proton and in another a positron. Inthe same time t, the work done on the two moving charged particles is        [NCERT Exemplar]

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 as compared to proton.We know that, work done = force x distance.As forces are same in case of proton and positron but distance moved by positron is larger, hence work done will be more.