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A plane electromagnetic wave of wavelength λ has an intensity I . It is propagating along the positive Y - direction. The allowed expressions for the electric and magnetic fields are given by:

Options

  1. AE → =   2   I ε 0 c   cos 2 π λ y - c t k ^ , B → = + 1 c E i ^
  2. BE → =     I ε 0 c   cos ⁡ 2 π λ y - c t k ^ , B → = + 1 c E i
  3. CE → =   2   I ε 0 c   cos 2 π λ y + c t k ^ , B → = + 1 c E i ^
  4. DE → =   I ε 0 c   cos 2 π λ y - c t i ^ , B → = + 1 c E k ^

Correct answer

A. E → =   2   I ε 0 c   cos 2 π λ y - c t k ^ , B → = + 1 c E i ^

Step-by-step solution

If E 0 is the amplitude of the electric field then the intensity of the electromagnetic wave is given as I = 1 2 ε 0 E 0 2 × c . From the above relation, we get E 0 =   2   I c   ε 0 . The relation between electric and magnetic fields is B 0 =   E 0 c . The direction of E → × B → will be along + j ^ .

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