Dual Nature of Radiation and Matter - Result Question 56
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60. The $21 cm$ 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
======= ####60. The $21 cm$ 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
3e0f7ab6f6a50373c3f2dbda6ca2533482a77bed:content/english/neet-pyq-chapterwise/physics/dual-nature-of-radiation-and-matter/dual-nature-of-radiation-and-matter—result-question-56.md (a) $10^{-17} J$
(b) $1 J$
(c) $7 \times 10^{-8} J$
(d) $10^{-24} J$
[1998]
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Answer:
Correct Answer: 60. (d)
Solution:
$ \text{ (d) } \begin{aligned} & E=h v=\frac{h c}{\lambda}=\frac{6.6 \times 10^{-34} \times 3 \times 10^{8}}{0.21} \\ & =\frac{6.6}{7} \times 10^{-24}=0.94 \times 10^{-24} J \end{aligned} $
