Physics Nuclear Physics MDCAT 2021
PMDC Verified Question 49 of 98
High speed beta rays are:
A
Electron
B
Positron
C
Electron and positron
D
Proton
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Electron


Concept:

Beta decay is a nuclear transmutation process. In standard terminology, "beta rays" default to beta-minus (\(\beta^{-}\)) particles unless specified otherwise.

Solution:

  • During \(\beta^{-}\) decay, a neutron in the nucleus converts into a proton, emitting a fast-moving particle to conserve charge.


  • This ejected particle has a charge of \(-1e\) and a mass equivalent to an electron.


  • Therefore, standard beta rays are simply streams of highly energetic electrons originating from the nucleus.


Why other options are incorrect:

While positrons are emitted in \(\beta^{+}\) decay, the historical and standard use of "beta ray" refers to the electron. Protons are heavy nucleons, not beta particles.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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