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NEET 1998 (AIPMT) · Other / Mixed: Atoms & Bohr Links

Other / Mixed: Atoms & Bohr Links question from NEET 1998 (AIPMT)

Q10NEET 1998 · AIPMTMedium

Other / Mixed: Atoms & Bohr Links

The 21 cm21\text{ cm} radio wave emitted by hydrogen in interstellar space is due to the interaction called the hyperfine interaction in atomic hydrogen. The energy of the emitted wave is nearly

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Answer: (d)

  1. E=hcλE = \frac{hc}{\lambda} with λ=0.21 m\lambda = 0.21\text{ m}.
  2. E=6.63×10−34×3×1080.21≈9.5×10−25 JE = \frac{6.63 \times 10^{-34} \times 3 \times 10^{8}}{0.21} \approx 9.5 \times 10^{-25}\text{ J}
  3. E≈10−24 JE \approx 10^{-24}\text{ J}
  4. So the answer is (d).
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