JEE Main 2021 · 24 February · evening · Single correct · +4 / −1
Match List - I with List - II.
Choose the correct answer from the options given below :
| List I | List II | ||
|---|---|---|---|
| (a) | Source of microwave frequency | (i) | Radioactive decay of nucleus |
| (b) | Source of infrared frequency | (ii) | Magnetron |
| (c) | Source of Gamma Rays | (iii) | Inner shell electrons |
| (d) | Source of X-rays | (iv) | Vibration of atoms and molecules |
| (v) | LASER | ||
| (vi) | RC circuit |
- (a) (a)-(vi), (b)-(v), (c)-(i), (d)-(iv)
- (b) (a)-(ii), (b)-(iv), (c)-(i), (d)-(iii)
- (c) (a)-(ii), (b)-(iv), (c)-(vi), (d)-(iii)
- (d) (a)-(vi), (b)-(iv), (c)-(i), (d)-(v)
Answer and solution
Answer (b) (a)-(ii), (b)-(iv), (c)-(i), (d)-(iii)
Solution
Physics sir · 4 steps
Match each wave to the physical process that makes it, and the option picks itself.
- Microwaves. Microwaves come from special vacuum tubes such as the klystron, magnetron and Gunn diode. So (a) goes with (ii).
- Infrared. Hot bodies give out infrared because their atoms and molecules vibrate. So (b) goes with (iv).
Radiation Produced by Match Microwave Magnetron (vacuum tube) (a)-(ii) Infrared Vibration of atoms and molecules (b)-(iv) Gamma rays Radioactive decay of the nucleus (c)-(i) X-rays Transitions of inner-shell electrons, or fast electrons stopped by a metal target (d)-(iii) - Gamma and X-rays. Gamma rays come from inside the nucleus, during radioactive decay. X-rays come from the atom's inner-shell electrons, when an outer electron drops into a vacancy near the nucleus. LASER and RC circuit match none of the four sources.
- So. The matching is (a)-(ii), (b)-(iv), (c)-(i), (d)-(iii), which is option (b).
The idea to keep. Each band has its own source: oscillating charges or tubes for radio and microwaves, vibrating molecules for infrared, inner electrons for X-rays, the nucleus for gamma rays.
Answer from the NTA final answer key. Solution by PrepWiser.