Electromagnetic waves - antennas

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Homework Help Overview

The discussion revolves around a problem involving electromagnetic waves and antennas, specifically focusing on a magnetic dipole used to detect an electromagnetic wave. The parameters include a coil antenna with specific turns and dimensions, along with the frequency and amplitudes of the electric and magnetic fields.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants are exploring how to calculate the induced emf in the coil, with some questioning the need for a time variable and discussing relevant equations, including Faraday's law of electromagnetic induction.

Discussion Status

The discussion is ongoing, with participants providing guidance on relevant concepts and equations. There is an acknowledgment of the correct equation to use, but uncertainty remains regarding the application of Faraday's law and the assumptions involved.

Contextual Notes

Some participants note the assumption of cosinusoidal time dependence in the magnetic induction, which may influence the approach to the problem.

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:

[tex]\varepsilon_m = N \omega A B[/tex]
 
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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