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Physics · Atomic Physics

JEE Main 2026 — 28 January, Evening Shift — Question 36

Number of photons of equal energy emitted per second by a 6 mW laser source operating at 663 nm is ____\_\_\_\_ . (Given : h=6.63×10−34\mathrm{h}=6.63 \times 10^{-34} J.s and c=3×108 m/s\mathrm{c}=3 \times 10^{8} \mathrm{~m} / \mathrm{s} )

  1. Option A:

    5×10165 \times 10^{16}

  2. Option B:

    5×10155 \times 10^{15}

  3. Option C:

    10×101510 \times 10^{15}

  4. Option D:

    2×10162 \times 10^{16}

    Correct

Answer: D

Step-by-step solution

P=nhCλ\mathrm{P}=\frac{\mathrm{nhC}}{\lambda} 6×10−3=n×6.63×10−34×3×108663×10−96 \times 10^{-3}=\frac{\mathrm{n} \times 6.63 \times 10^{-34} \times 3 \times 10^{8}}{663 \times 10^{-9}} n=2×1016\mathrm{n}=2 \times 10^{16} photons

Answer key and solution verified before publishing.

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Exam
JEE Main 2026
Paper
28 January, Evening Shift
Subject
Physics
Chapter
Atomic Physics
Topic
Photon Theory of Light and Radiation Pressure
Number of photons of equal energy emitted per second by a 6 mW laser… | JEE Main 2026 PYQ with Solution · DhiX AI