GATE 2023 PH – Question 39
Match the radiation to its processes.
| Column 1 | Column 2 |
|---|---|
| (i) Visible light | P. Core atomic transitions |
| (ii) X-rays | Q. Nuclear transitions |
| (iii) Gamma rays | R. Pair production |
| (iv) Thermal neutrons | S. Crystal structure determination; T. Photoelectric effect |
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Correct answer: (A) (i) - T; (ii) - P,S,T; (iii) - Q,R; (iv) - S
Explanation
Match each radiation or probe with the processes it takes part in.
- **(i) Visible light:** its photons (about 2 to 3 eV) are energetic enough to eject electrons from some metals, so the **photoelectric effect** (T) applies. (i)-T.
- **(ii) X-rays:** produced by transitions between **core atomic levels** (P), diffracted by crystals to determine their **crystal structure** (S), and able to cause the **photoelectric effect** (T). (ii)-P, S, T.
- **(iii) Gamma rays:** emitted in **nuclear transitions** (Q), and above 1.022 MeV they can undergo **pair production** (R). (iii)-Q, R.
- **(iv) Thermal neutrons:** their de Broglie wavelength is comparable to the atomic spacing, so they are used for **crystal structure determination** (S). (iv)-S.
Match: **(i)-T; (ii)-P,S,T; (iii)-Q,R; (iv)-S** (option A).