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How to determine the direction of the induced current or direction of induced magnetic field in a coil from a permanent magnet?

Physics Asked on January 4, 2021

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So the inducing magnetic field points upwards since the field travel south to north in a magnet. The inducing magnetic flux also increases as it heads towards the coil. According to Lenz’s Law, the direction of the induced current is such that its magnetic field opposes the change in the magnetic flux that created it.

So I say the induced magnetic flux will travels downwards. As a result the induced current, will travel clockwise.

But according to the solution provided by my textbook which is demonstrated below, my reasoning is incorrect:
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So who is correct? Is there any misconception from my part? Because my reasoning seems valid to me. Please

One Answer

(a) The first line in the table from your textbook is wrong. The flux from the magnet is upwards through the coil and increasing. It is true that the magnetic field lines will curve round and return to the South pole, but most of the lines will go upwards through the coil before curving back downwards and returning outside the coil. [The textbook-writer would have done well to sketch some of the magnet's field lines.]

(b) Clockwise and anticloclockwise (counterclockwise) are ambiguous terms. You have reasoned correctly that the induced current in the coil is clockwise, but this is when the coil is viewed from above. Viewed from below it is anticlockwise. So you need to state from which direction you are viewing. There are exceptions, such as when talking about going round a 'circular' walk, because no-one would consider viewing the walk from underground. At least I don't think they would...

Correct answer by Philip Wood on January 4, 2021

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