If the magnetic field in a plane electromagnetic wave is along the y axis and it
ID: 1566983 • Letter: I
Question
If the magnetic field in a plane electromagnetic wave is along the y axis and its magnitude is given byBmsin (kx – wt) in SI units, then the electric field is along the z axis and its magnitude is given by?
My answer is A, I am not sure if this is correct?
I saw many answers are in the positive direction, could anyone explain why is it in positive? I think should be in the negative direction. We know that the sin(kx-wt) is in the positive direction which means C is in the positive x direction. E must be in negative z direction so that E X B will make the C to be in the positive direction.
Do I make any statements wrong?
A) –(cBm) sin (kx – wt)
B) (cBm) sin(kx – wt)
Explanation / Answer
E = cB
Given that, B=BmSin(kx-t)
Therefore,
E = cBmSin(kx-t)
The question is asking about the magnitude of electric field and magnitude cannot be negative.
Therefore, option (b) is the correct answer