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NEETPhysicsElectromagnetic Waves

In an electromagnetic wave propagating in vacuum, what fraction of the total average energy density is contributed by the electric field component? (where c is the speed of light in vacuum)

Options

  1. A1 c
  2. Bc 1+c
  3. C1 2
  4. D1 c^2

Correct answer

C. 1 2

Step-by-step solution

In an electromagnetic wave, the energy is equally divided between the electric and magnetic fields. The average energy density of the electric field ( u_E ) is equal to the average energy density of the magnetic field ( u_B ). Total average energy density, u = u_E + u_B = 2u_E Therefore, the fraction of the total energy density contributed by the electric field is u_E u = u_E 2u_E = 1 2 . Answer: 1 2

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