Dual Nature of Radiation and Matter - Result Question 56
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
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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
c3eec34ec6b1fad69db54a20ad4b2dca40c2aa54 (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} $
