Monochromatic light of frequency $$6 \times 10^{14}$$ Hz is produced by a laser. The power emitted is $$2 \times 10^{-3}$$ W. How many photons per second on an average, are emitted by the source? (Given $$h = 6.63 \times 10^{-34}$$ J s)

We need to find the number of photons emitted per second by a laser of frequency $$\nu = 6 \times 10^{14}$$ Hz and power $$P = 2 \times 10^{-3}$$ W.

The energy of one photon is given by $$E = h\nu = 6.63 \times 10^{-34} \times 6 \times 10^{14} = 39.78 \times 10^{-20} \approx 3.978 \times 10^{-19}$$ J.

Consequently, the number of photons emitted per second is $$n = \frac{P}{E} = \frac{2 \times 10^{-3}}{3.978 \times 10^{-19}} = \frac{2}{3.978} \times 10^{16} \approx 0.503 \times 10^{16} = 5.03 \times 10^{15},$$ so that $$n \approx 5 \times 10^{15}.$$

The correct answer is Option C) $$5 \times 10^{15}$$.