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JEE Main 201212 MayOnline
Exam
JEE Main
Year
2012
Date
12 May
Mode
Online
Subject
Physics
Chapter
Communication System

JEE Main 2012 · 12 May · Online · Physics · Communication System

A 10 ~kW transmitter emits radio waves of wavelength 500 ~m . The...

A 10 kW10 \mathrm{~kW} transmitter emits radio waves of wavelength 500 m500 \mathrm{~m}. The number of photons emitted per second by the transmitter is of the order of

Options

  1. A103710^{37}
  2. B103110^{31}
  3. C102510^{25}
  4. D104310^{43}

Correct answer

B. 103110^{31}

Step-by-step solution

Power =nhcλ=\frac{n h c}{\lambda} (where, n=n= no. of photons per second) \Rightarrow \quad n=10×103×5006.6×10−34×3×108≃\frac{10 \times 10^3 \times 500}{6.6 \times 10^{-34} \times 3 \times 10^8} \simeq10^{31}
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