Electromagnetic waves - antennas

AI Thread Summary
To determine the amplitude of the induced emf in a coil antenna detecting an electromagnetic wave, the relevant parameters include a magnetic dipole, coil specifications, and wave characteristics. The coil has 50 turns and a radius of 5.0 cm, while the EM wave has a frequency of 870 kHz and specific electric and magnetic field amplitudes. The correct approach involves applying Faraday's law of electromagnetic induction, specifically using the equation ε_m = NωAB. A cosine time dependence of the magnetic induction is assumed for simplification. Understanding these concepts is essential for solving the problem effectively.
evan4888
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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?
 
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I think you might need a review of the Faraday's electromagnetic induction law.

Daniel.
 
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 without a variable of time.

Or would I just use the equation:

\varepsilon_m = N \omega A B
 
Last edited:
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.
 
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