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In the following picture current is flowing through coil 1. Let's assume that current is increasing linearly in coil 1. Then emf induced in 2nd coil be will constant and having some negative value. What would be the flux in coil 2? How it could be interpreted in graphs and what's reason behind the behaviour? enter image description here

Ahsan
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What would be the flux in coil 2?

The flux in coil 2 is produced entirely from the current flowing in in coil 1 hence, if you know what the flux coupling factor (k) is, coil 2's flux is coil 1's flux multiplied by k.

Andy aka
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  • Does emf have any effect on flux? As the current in coil 1 is increasing or decreasing, consequently the emf in coil 2 will be negative or positive due to which current direction changes and flux in coil 2 will also change... – Ahsan Oct 05 '20 at 15:16
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    Only current in coil 2 will affect the flux. An open circuit emf is of no-consequence. – Andy aka Oct 05 '20 at 15:21
  • Let the current in coil 1 is increasing linearly. The current in coil 2 will be in opposite direection so that magnetic field will tend to oppose the magnetic field of coil 1. As the magnetic flux will be in opposite direction in coil 2. In that case the coupling coefficient is also valid? How? – Ahsan Oct 05 '20 at 15:24
  • @Ahsan I'm sorry but this site isn't a forum and you now appear to evolving what you want to know into much more seriously mathematical areas. I'm just saying this in case you thought stack exchange was some coaching site. To answer this you need to look at the theories of mutually coupled inductors. Sure the net flux will lower in coil 2 when current is drawn from coil 2 but the current in coil 1 will also increase to counter flux_2 and that will tend to try and cancel the negative effects of coil 2's flux. It gets mathematical pretty much straight away and somewhat non-intuitive. – Andy aka Oct 05 '20 at 15:56
  • k will remain constant throughout. Voltage across coil 2 will drop with coil 2's current but k remains fixed. The voltage across coil 2 is directly a measure of the net flux coil 2 sees. – Andy aka Oct 05 '20 at 16:02
  • I have gone through the theory. I got good concepts regarding emf but uanble to get concept of flux in coil 2. So according to that if current through coil 1 is increasing then flux through coil 2 is increasing but in opposite direction so overall flux will remain same? – Ahsan Oct 05 '20 at 16:18
  • Whatever the voltage seen across coil 2 - that is representative of the flux that it receives. If that voltage drops (due to a load on coil 2 and hence current) then the flux that coil 2 sees must also be reduced in proportional to the voltage. But, because the self inductance of coil 2 is also a factor and is in series with the load it forms a potential divider with the load so, you can't directly infer flux from terminal voltage unless you know the inductance. – Andy aka Oct 05 '20 at 17:06
  • Let us [continue this discussion in chat](https://chat.stackexchange.com/rooms/113758/discussion-between-ahsan-and-andy-aka). – Ahsan Oct 05 '20 at 18:23
  • This site isn't a talking shop. Your basic question has been answered plus a few more. Time to move on with a newer question and formally mark this one as accepted. Oh, I see you might have gotten out of the habit of accepting answers since April. I suggest you review your later questions and mark those that have good answers. – Andy aka Oct 06 '20 at 07:44