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Electromagnetic Induction Comprehension problem

Test your understanding!

When the south pole of the bar magnet is brought nearer to the coil, the galvanometer needle is deflected to right. In which direction will it deflect when the north pole of the magnet is moved away from the coil?

Consider an S-pole approaching a coil. The field on the coil is increasing. An emf is produced in the coil due to change (increase) in the flux. The emf will be producing current in the coil. The direction of the current will be such that its magnetic field will oppose the increase in the flux, thereby trying to push the S-pole back. This means the magnetic field due to current in the coil will face the same S-pole towards the bar magnet. The direction of the current will be clockwise as shown from magnet side.

Now the deflection in the galvanometer is related to the direction of the current. Therefore, if the direction of the current is clockwise, the direction of deflection of the galvanometer is to the right.

Now consider the N-pole withdrawn from the coil. The flux on the coil is decreasing (changing). Due to this change in the flux over the coil, an emf is produced in the coil. The current developed due to this emf will have direction in such a way to increase the flux, thereby to attract the magnet. Since an S-pole will attract the withdrawing N-pole, therefore, the face towards the bar magnet will again be the S-pole. This means the current in the coil flows in the same clockwise direction. Therefore, the deflection in the galvanometer will again be the same, i-e, towards the right.

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