Homework Help: Why there's a reading on the voltmeter connected to coil Q?

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1. May 1, 2017

1. The problem statement, all variables and given/known data
The current in coil P is constant. An iron rod is inserted into coil P. Coil Q is placed next to P with a voltmeter connected to it. Explain why, during the time that the rod is moving, there is a reading on the voltmeter connected to coil Q

2. Relevant equations
emf=-Dphi/dt

3. The attempt at a solution
I believe that the Iron rod will first be magnetised and then the magnetic lines originating from Iron will cause a change of flux in coil Q.

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Last edited by a moderator: May 1, 2017
2. May 1, 2017

CWatters

Find the equation for the magnetic field produced by a coil/solenoid. What does it depend on? What is changing in this set up?

3. May 1, 2017

The equation is B=uIn, and none of the u and n are constant. Current is changing due to change of flux inside the coil P as Iron screens the magnetic lines of P?

4. May 1, 2017

CWatters

The number of turns n is constant, as is the length l.

What do you know about the relative permeability u?

5. May 1, 2017

CWatters

PS it's nothing to do with "screening".

6. May 5, 2017

rude man

Nope.
Reconsider post 2. Diligently.