- #1

khfrekek92

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## Homework Statement

So I'm trying to figure out this problem:

The base of our charging station is composed of a coil with N1 turns and area A1 connected to a 120 VAC, 60 Hz source. The device has a smaller coil with N2 turns and area A2, which when attached will fit completely inside the charging coil.

A) What is the EMF of the base coil?

B) what is the EMF of the device coil?

C) how many turns do you need In the second coil to get a 6 vac RMS source?

## Homework Equations

B_loop=N*mu*I/(2*R)

EMF=d(flux)/dt

## The Attempt at a Solution

A) What is the EMF of the base coil?

This should be 0, right? No changing flux is actually going through this coil.

B) what is the EMF of the device coil?

B1 from the outer loop is : N1mu*I/(2*R1), so the RMS EMF through this loop is d/dt(B1*A2)=N1*mu*A2*omega*I_peak/(2*sqrt(2)*R1).

C) how many turns do you need In the second coil to get a 6 vac RMS source?

?

My questions are:

did I do A) right? Is the EMF 0 in the base coil?

And as for part B), the problem states that the resistance of the loop is negligible, and my final answer is in terms of I. Unfortunately the problem gave me the voltage (120V) of the ac power source, so how do I get the current?

And on Part C), I don't see how to factor in the number of coils on the second loop.. did I do part B) correct?

Thanks so much in advance!