Question

Monochromatic light of frequency $6.0\times {10}^{14}$ Hz is produced by a laser. The power emitted is $2\times {10}^{-3}$W. The number of photons emitted, on the average, by the source per second is:

• A. $5\times {10}^{14}$
• B. $5\times {10}^{15}$
• C. $5\times {10}^{16}$
• D. $5\times {10}^{17}$

Answer 1

The correct option is B $5\times {10}^{15}$

No. of photoelectrons emitted, $n=\frac{p}{hv}.=\frac{2\times {10}^{-3}}{6.62\times {10}^{-34}\times 6\times {10}^{14}}=5\times {10}^{15}$