Monochromatic light of frequency 6.0 × 1014 Hz is produced by a laser. The power emitted is 2 × 10 - 3 W. The number of photons emitted, on the average, by the source per second is (a) 5 × 10¹⁶ (b) 5 × 10¹⁷ (c) 5 × 10¹⁴ (d) 5 × 10¹⁵

Answer: (d). E = hν = (6.63 × 10⁻³⁴)(6 × 10¹⁴) = 3.98 × 10⁻¹⁹ J n = P/E = 2 × 10⁻³3.98 × 10⁻¹⁹ ≈ 5 × 10¹⁵ s⁻¹ So the answer is (d) 5 × 10¹⁵.

Monochromatic light of frequency 6.0 × 1014 Hz is produced by a… | NEET 2007 (AIPMT)

Q37NEET 2007 · AIPMTEasy

Photons: Energy, Momentum & Radiation Pressure

Monochromatic light of frequency 6.0 $\times$ 1014 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

Show answer and solution

Answer: (d)

$E = h\nu = (6.63 \times 10^{-34})(6 \times 10^{14}) = 3.98 \times 10^{-19}\text{ J}$
$n = \frac{P}{E} = \frac{2 \times 10^{-3}}{3.98 \times 10^{-19}} \approx 5 \times 10^{15}\text{ s}^{-1}$
So the answer is (d) $5 \times 10^{15}$ .

Report a mistake

Photons: Energy, Momentum & Radiation Pressure question from NEET 2007 (AIPMT)

More questions on Photons: Energy, Momentum & Radiation Pressure