2017 · Q11
An electron and a proton starting from rest are accelerated through a potential difference of 1000 V. Which one of the following statements in this regard is correct ?
General KnowledgePhysics
- AThe kinetric energy of both the particles will be different.
- BThe speed of the electron will be higher than that of the proton.
- CThe speed of the proton will be higher than that of the electron.
- DThe speed of the electron and the proton will be equal.
Explanation
Each particle carries charge of magnitude e, so both gain the same kinetic energy, eV = 1000 eV, on acceleration through 1000 V — ruling out the claim that their kinetic energies differ. With equal kinetic energy (1/2)mv², speed is v = √(2K/m), so the lighter particle moves faster. The electron's mass (about 9.1×10⁻³¹ kg) is roughly 1836 times smaller than the proton's. The electron therefore emerges with a much higher speed than the proton.