How many of the following statements about gamma rays are correct?
(A) Gamma rays are electromagnetic waves.
(B) Gamma rays are emitted by radioactive nuclei.
(C) Gamma rays are used in medicine to destroy cancer cells.
(D) Gamma rays lie in the lower frequency range of the electromagnetic spectrum.
(E) Gamma rays travel through vacuum faster than visible light.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 3
Gamma rays lie beyond the X-ray region of the electromagnetic spectrum.
The statements that are correct:
(A) Electromagnetic waves — gamma rays are a part of the electromagnetic spectrum.
(B) Emitted by radioactive nuclei — they are produced in nuclear reactions and given out by radioactive nuclei.
(C) Used against cancer — in medicine they are used to destroy cancer cells.
The statements that are not correct:
(D) — gamma rays lie in the upper frequency range of the spectrum, with wavelengths below about \( 10^{-10}\,\mathrm{m} \). The lowest frequencies belong to radio waves.
(E) — all electromagnetic waves, gamma rays and visible light alike, travel through vacuum with the same speed \( c \).
Number of correct statements = 3
NCERT (2026-27):
Gamma Rays – “They lie in the upper frequency range of the electromagnetic spectrum and have wavelengths of from about 10–10m to less than 10–14m. This high frequency radiation is produced in nuclear reactions and also emitted by radioactive nuclei. They are used in medicine to destroy cancer cells.”
Summary – “Light is an electromagnetic wave; c is, therefore, also the speed of light. Electromagnetic waves other than light also have the same velocity c in free space.”