Physics Circle home Student Login

Home›Chapters›Dual Nature of Radiation and Matter PYQs›Photons: Energy, Momentum & Radiation Pressure›Question 1

MHT CET 2026 (15 May, Shift 2) · Photons: Energy, Momentum & Radiation Pressure

Photons: Energy, Momentum & Radiation Pressure question from MHT CET 2026 (15 May, Shift 2)

Q1MHT CET 2026 · 15 MAY · SHIFT 2Easy

Photons: Energy, Momentum & Radiation Pressure

The number of photons per second emitted by the source of monochromatic light of wavelength 600600 nm, when it delivers the power of 3.3×10−33.3 \times 10^{-3} W will be

(Planck's constant =6.6×10−34= 6.6 \times 10^{-34} Js, c=3×108c = 3 \times 10^{8} m/s)

Show answer and solution

Answer: (b)

  1. Energy per photon E=hcλ=(6.6×10−34)(3×108)600×10−9=3.3×10−19 JE = \frac{hc}{\lambda} = \frac{(6.6 \times 10^{-34})(3 \times 10^{8})}{600 \times 10^{-9}} = 3.3 \times 10^{-19}\text{ J}
  2. n=PE=3.3×10−33.3×10−19=1016 s−1n = \frac{P}{E} = \frac{3.3 \times 10^{-3}}{3.3 \times 10^{-19}} = 10^{16}\text{ s}^{-1}
  3. So the answer is (b) 101610^{16}.
Report a mistake

More questions on Photons: Energy, Momentum & Radiation Pressure