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Because relative motion between the two is causing current to flow in the coil, would there be any electromagnetic induction in the coil when both coil and magnet move simultaneously in opposite directions with equal speeds? Will the induced current be more than the standard induction model or will it be cancelled out in such configuration?

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2 Answers 2

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Whether you move a magnet towards a stationary solenoid with a speed $v$ or move a solenoid towards a stationary magnet with the same speed $v$, the induced current in both the cases is similar. It all depends on the relative velocity of the magnet with respect to the solenoid.

When both solenoid and magnet move towards each other with a speed $v$, the relative speed of one with respect to the other is $2v$. Clearly the induced current is larger in this case compared to moving only the magnet or the solenoid with a speed $v$ towards the other. However, the induced current in this case is similar when you move either the magnet or the solenoid towards the other (which is stationary) with a speed $2v$.

Also when you move both the magnet and the solenoid in the same direction with the same speed, the relative speed between them is zero and hence this is similar to both the magnet and the coil at rest, and there will be no induced current.

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  • $\begingroup$ Ok thanks, yet I had a feeling that current will be zero (canceled out) because two currents will be induced: one current coming from right direction and other from left direction and electrons cant flow against each other in wire so no current will flow when both things move. Can you post a link to such experiment as proof? I cant find it, all I can see is typical faraday induction pictures. $\endgroup$ May 11, 2020 at 11:38
  • $\begingroup$ @MarcinPająk: When there is only one magnet, there is only one direction along which the induced current would flow. This case is much similar to the classic experiment if you look at the magnet from the solenoid's reference frame. Of course, moving the magnet or the solenoid the other way would induce an opposite current but that's a separate case. I don't understand what is the other current (you are referring to) which is produced in the opposite direction, simultaneously, to "cancel out" the effects of the induced current? $\endgroup$
    – Vishnu
    May 11, 2020 at 11:43
  • $\begingroup$ Coil is cutting magnet field lines and magnet field lines are cutting wire at the same time, this lead me to conclusion that two currents would appear. From perspective of the coil only magnet move from left to right and from perspective of the magnet only coil move from right to left so finally magnet induced/pushed current in coil from left side and coil induced/pushed another current in itself from right side, to currents pushing against each other thus 0 voltage, similar to "out of phase" two transformers action. $\endgroup$ May 11, 2020 at 12:03
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Whether you move a magnet towards a stationary solenoid with a speed v or move a solenoid towards a stationary magnet with the same speed v, the induced current in both the cases is similar. It all depends on the relative velocity of the magnet with respect to the solenoid.

When both solenoid and magnet move towards each other with a speed v, the relative speed of one with respect to the other is 2v. Clearly the induced current is larger in this case compared to moving only the magnet or the solenoid with a speed v towards the other. However, the induced current in this case is similar when you move either the magnet or the solenoid towards the other (which is stationary) with a speed 2v.

Also when you move both the magnet and the solenoid in the same direction with the same speed, the relative speed between them is zero and hence this is similar to both the magnet and the coil at rest, and there will be no induced current

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