Dual Nature of Radiation and Matter - Result Question 38
40. A source $S_1$ is producing, $10^{15}$ photons per second of wavelength $5000 \AA$. Another source $S_2$ is producing $1.02 \times 10^{15}$ photons per second of wavelength $5100 \AA$ Then, (power of $S_2$ ) (power of $S_1$ ) is equal to :
[2010]
(a) 1.00
(b) 1.02
(c) 1.04
(d) 0.98
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Answer:
Correct Answer: 40. (a)
Solution:
- (a) Energy emitted/sec by $S_1, P_1=n_1 \frac{h c}{\lambda_1}$
Energy emitted/sec by $S_2, P_2=n_2 \frac{h c}{\lambda_2}$
$\therefore \quad \frac{P_2}{P_1}=\frac{n_2}{n_1} \cdot \frac{\lambda_1}{\lambda_2}$
$ =\frac{1.02 \times 10^{15}}{10^{15}} \cdot \frac{5000}{5100}=1.0 $
