Question

An electromagnetic wave is propagating in a medium with velocity \( \vec{v} = v \hat{i} \). The instantaneous oscillating magnetic field of this electromagnetic wave is along positive \( z \)-direction. Then the direction of the oscillating electric field is in the:

• A. positive \( x \)-direction
• B. negative \( x \)-direction
• C. positive \( y \)-direction
• D. negative \( y \)-direction
• E. negative \( z \)-direction

Hint:

For electromagnetic waves, the directions of the electric field, magnetic field, and wave propagation follow the right-hand rule, with all three directions being mutually perpendicular.

Answer 1

The Correct Option is C

Step 1: For electromagnetic waves, the electric field \( \vec{E} \), the magnetic field \( \vec{B} \), and the propagation direction \( \vec{v} \) are all mutually perpendicular. Step 2: Given that the magnetic field oscillates in the \( z \)-direction and the wave propagates in the \( x \)-direction, the electric field must oscillate in the \( y \)-direction to satisfy the right-hand rule for electromagnetic waves. 
Thus, the direction of the oscillating electric field is in the positive \( y \)-direction.