The main constituent of cosmic ray is
(A) proton
(B) meson
(C) alpha particle
(D) neutrino
The correct answer is: (A) proton
Explanation:
Cosmic rays are high-energy particles that originate from outer space and strike the Earth’s atmosphere. Their main constituent is:
- Protons (hydrogen nuclei), which make up about 90% of primary cosmic rays.
- Alpha particles (helium nuclei) account for about 9%.
- The remaining ~1% includes heavier nuclei, electrons, and a tiny amount of antiparticles.
Other particles like mesons and neutrinos are produced secondarily when primary cosmic rays (mostly protons) interact with atoms in the Earth’s atmosphere.
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