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NEET2026PhysicsChapterActual

In a certain region of space, a plane electromagnetic wave is observed to travel along the negative z -axis. Identify the valid combination of directions for the electric field ( E ) and the magnetic field ( B ) respectively, from the given choices.

Options

  1. Ai + j , - i + j
  2. Bi - j , i + j
  3. Ci + j , i - j
  4. D- i + j , - i - j

Correct answer

C. i + j , i - j

Step-by-step solution

The direction of propagation of an electromagnetic wave is given by the direction of the Poynting vector, which is parallel to E B . Since the wave is traveling along the negative z -axis, the direction of E B must be - k . Also, the electric field E and magnetic field B must be mutually perpendicular, so E B = 0 . Checking the given options: For E = i + j and B = i - j : E B = (1)(1) + (1)(-1) = 0 E B = ( i + j ) ( i - j ) = - i j + j i = - k - k = -2 k The direction of E B is along - k , which corresponds to the

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