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Question: Answered & Verified by Expert
Assume that a lamp radiates power P uniformly in all directions. The magnitude of electric field strength at a distance r from the lamp is
PhysicsElectromagnetic WavesNEET
Options:
  • A Pπcε0r2
  • B P2πcεr2
  • C P2πε0r2c
  • D Pπε0cr2
Solution:
2705 Upvotes Verified Answer
The correct answer is: P2πε0r2c
Intensity, I=powerarea=P4πr2 = average energy density × velocity=12ε0E02c

E0=2P4πε0r2c=P2πε0r2c

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