The GATE Grind

GATE 2014 EC (EC2) – Question 35

Electromagnetics · Plane Waves and Properties · 1 mark · Multiple choice

Which TEM field pattern travels in the positive x direction?

  1. $\mathbf E=8\hat y,\ \mathbf H=-4\hat z$
  2. $\mathbf E=-2\hat y,\ \mathbf H=-3\hat z$
  3. $\mathbf E=2\hat z,\ \mathbf H=2\hat y$
  4. $\mathbf E=-3\hat y,\ \mathbf H=4\hat z$

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: (B) $\mathbf E=-2\hat y,\ \mathbf H=-3\hat z$

Explanation

Power propagates in the direction of E×H. For **E=−2ŷ,H=−3ẑ,B**, the cross product is(+6)x̂ because ŷ×ẑ=x̂ and the two minus signs cancel. The other listed field pairs give a negative x-directed cross product.