Question

An electromagnetic wave is transporting energy in the negative y direction. At one point and one instant the magnetic field is in the positive x direction. The electric field at that point and instant is:Why is (D) the answer? I thought it's (C)A) positive y directionB) negative y directionC) positive z directionD) negative z direction

Answer 1

Answer:negative Z direction

Explanation:

It is given that EM wave is travelling in negative y direction i.e. -$\hat{j}$

Magnetic Field is in positive x direction i.e. $\hat{i}$

We know that Electric field and magnetic field are perpendicular to each other and they are mutually perpendicular to direction of wave propagation.

Mathematically if Electric field is in negative z direction it will yield the direction of wave propagation

$=(-\hat{k})\times \hat{i}$

$=-\hat{j}$