# Homework Help: Electromagnetic waves - antennas

1. Jul 12, 2005

### evan4888

I just need a little direction to get started on this problem.

A magnetic dipole is uded to detect an electromagnetic wave. The antenna is a coil of 50 turns with radius 5.0 cm. The EM wave has frequency 870 kHz, electric field amplitude 0.50 V/m, and magnetic field amplitude 1.7 x 10^-9 T.

What is the amplitude of the induced emf in the coil?

2. Jul 12, 2005

### dextercioby

I think you might need a review of the Faraday's electromagnetic induction law.

Daniel.

3. Jul 12, 2005

### evan4888

I will need a little more guidance than that. I am thinking that I need to find the emf, but I am not sure how I could do that with out a variable of time.

Or would I just use the equation:

$$\varepsilon_m = N \omega A B$$

Last edited: Jul 12, 2005
4. Jul 12, 2005

### dextercioby

That's the right equation indeed and it follows really nicely, if you apply Faraday's law correctly and assume, for simplicity a cosinusoidal time dependence of the magnetic induction.

Daniel.