Electromagnetic waves - antennas

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SUMMARY

The discussion focuses on calculating the amplitude of the induced electromotive force (emf) in a magnetic dipole antenna designed to detect electromagnetic waves. The antenna consists of a coil with 50 turns and a radius of 5.0 cm, operating at a frequency of 870 kHz, with an electric field amplitude of 0.50 V/m and a magnetic field amplitude of 1.7 x 10^-9 T. Participants confirm the use of the equation ε_m = NωAB, derived from Faraday's law of electromagnetic induction, to compute the induced emf.

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  • Understanding of Faraday's law of electromagnetic induction
  • Familiarity with electromagnetic wave properties
  • Knowledge of coil parameters (turns, radius)
  • Basic grasp of sinusoidal functions in physics
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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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