RAS question
The phenomenon of 'Quantum Tunnelling' is:
Correct answer: (C) A particle passing through a potential energy barrier that it classically could not surmount.
Quantum tunnelling is the quantum-mechanical phenomenon in which a particle passes through a potential energy barrier that classical mechanics says it could not surmount.
Explanation
Quantum tunnelling is not a literal tunnel or a communication technology; it is a consequence of quantum mechanics. Particles can cross energy barriers that would be impossible in classical mechanics because of wave-particle duality. The Department of Energy, Office of Science - DOE Explains...Electrons notes that electrons can appear on the opposite side of a barrier because they behave as both particles and waves, so part of the wave can be beyond the barrier. That is why option C is precise: it identifies the barrier, the particle, and the contrast with classical mechanics. The core idea is probability at the quantum scale, not mechanical digging, optical transmission, or encryption.
Why the other options are wrong
- (A) Quantum tunnelling is a microscopic physics phenomenon, so it does not mean digging physical tunnels with quantum computers.
- (B) An optical fibre is a light-guiding medium, whereas quantum tunnelling describes a particle crossing a potential energy barrier.
- (D) Quantum encryption concerns secure communication, while tunnelling is about particle behaviour under quantum mechanics.
Concept
This tests the RAS Science and Technology concept of basic quantum phenomena, especially the break between classical and quantum explanations. It recurs because exam questions often check whether candidates can distinguish real scientific terms from plausible-sounding technology labels.