Dual Nature Of Matter Question 2
Question 2 - 2024 (01 Feb Shift 2)
Monochromatic light of frequency $6 \times 10^{14} \mathrm{~Hz}$ is produced by a laser. The power emitted is $2 \times 10^{-3} \mathrm{~W}$.
How many photons per second on an average, are emitted by the source?
(Given $\mathrm{h}=6.63 \times 10^{-34} \mathrm{Js}$ )
(1) $9 \times 10^{18}$
(2) $6 \times 10^{15}$
(3) $5 \times 10^{15}$
(4) $7 \times 10^{16}$
Show Answer
Answer: (3)
Solution:
$\mathrm{P}=\mathrm{nh} \nu$
$\mathrm{n}=\frac{\mathrm{P}}{\mathrm{hv}}=\frac{2 \times 10^{-3}}{6.63 \times 10^{-34} \times 6 \times 10^{14}}$
$=5 \times 10^{15}$
