- #1
Deep_Thinker97
- 11
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Currently doing my A2 Levels and have just been revising over electromagnetic induction. The general consensus seems to be that current can only be induced in a changing magnetic flux.The textbook I'm using constantly refers to cutting a magnetic field, i.e. moving a wire relative to a field, to induce current. But the only way I can see this working is if the field is non uniform. If a wire were to cut a non uniform field (by moving in a straight line), since magnetic field strength is different along its course of motion, then the magnetic flux 'felt' by the wire is changing, thus meeting to requirements for electromagnetic induction. However, if a wire was to cut a uniform magnetic field (that is going from left to right say), by moving its length downwards through the magnetic field, surely no current would be induced, since the field strength remains constant along its course of motion and so magnetic flux does not change. In fact, my textbook actually has questions that refer to this example: e.g. 'The uniform field between the poles of a magnet has flux density of 0.062T. A wire of length 5.3cm is moved down a distance of 2.8cm in 0.060s. Calculate the EMF and the current induced'. I understand how to work through this question, using faraday law etc, but I don't understand why any EMF/current would be induced in the first place for the reasons explained previously.
So its either the idea that current can only be induced via changing magnetic flux is wrong, because it can also be induced by just moving a wire relative to a uniform field, OR the questions in my textbook are just poorly formulated.
I think its the latter but I'm not sure. Any help?
So its either the idea that current can only be induced via changing magnetic flux is wrong, because it can also be induced by just moving a wire relative to a uniform field, OR the questions in my textbook are just poorly formulated.
I think its the latter but I'm not sure. Any help?