2019 · Q61
An electron and a proton starting from rest get accelerated through potential difference of 100 kV. The final speeds of the electron and the proton are V and V respectively. Which one of e p the following relations is correct?
General KnowledgePhysics
- AV > V e p
- BV < V e p
- CV = V e p
- DCannot be determined
Explanation
Both particles start from rest and gain the same kinetic energy qV from the 100 kV potential difference. Since kinetic energy is (1/2)mv^2, the speed is v = sqrt(2qV/m). The electron's mass is far smaller than the proton's, so the electron attains the greater speed. Hence Ve > Vp, and option A is correct.