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NEETPhysicsElectromagnetic Waves

Assertion (A): For an electromagnetic wave propagating in vacuum along the negative z-axis, if the electric field is along the positive x-axis, then the magnetic field must be along the positive y-axis. Reason (R): The direction of propagation of an electromagnetic wave is given by the vector E B , and the electric and magnetic fields are mutually perpendicular. In the light of the above statements, choose the most a

Options

  1. ABoth Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A)
  2. BBoth Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A)
  3. CAssertion (A) is true but Reason (R) is false
  4. DAssertion (A) is false but Reason (R) is true

Correct answer

D. Assertion (A) is false but Reason (R) is true

Step-by-step solution

The direction of propagation of an electromagnetic wave is given by the cross product of the electric and magnetic field vectors, i.e., v E B . Given that the wave propagates along the negative z-axis, the direction of propagation is - k . The electric field is along the positive x-axis, so E is along + i . We need to find the direction of B such that i B = - k . Since i j = k , it follows that i (- j ) = - k . Therefore, the magnetic field must be along the negative y-axis ( - j ). The Assertion states that the ma

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