# Homework Help: Finding H field from E field

1. Sep 3, 2015

### lcr2139

1. The problem statement, all variables and given/known data

E (Vector) = 18.85*cos(omega*t - 15*z) a_x (unit vector)
Find H(vector) field

2. Relevant equations

I tried ∇ X H = -dD/dt, in which I take the derivative of E(vector). How do I pull H from the curl?

3. The attempt at a solution

I took the derivative of -dD/dt, and came up with ∇ X H . I used the matrix to find the partial derivative of H, but I do not know how to find H from the partial derivative. Also, I do not know how to find the direction of H.

2. Sep 3, 2015

### blue_leaf77

Try another equation from the Maxwell's equations which enables you to calculate H easily from E.

3. Sep 5, 2015

### rude man

The way to arrive at H is indeed to employ the other major Maxwell equation. But the math is a bit extensive. In your course work you probably derived, or saw derived, the simple relation between the H and E fields of a plane wave.

4. Nov 12, 2015

### Muhammet

Curl of E equals to derivative of H multipled by -permeability. So, take the curl of E, divide to -permeability, then take the integral of that , you have H now.