Electromagnetic Induction | AC Generator (Alternator) | A-level Physics

[@ForestLearn]

Answer to question posed at 8:59 (please try to figure it out yourself before taking a look!): To understand why the current alternates viewed through the lens of Lenz's law (!), it's helpful to recall the informal version of the law (for changes in flux) discussed in this vid [ kzbin.info/www/bejne/r2PGZGmNbrabsKc ]: 'The coil/loop tries to *oppose* any *changes* in magnetic flux (linkage).' As the north pole of the rotating magnet approaches the coil, the coil tries to oppose the changing flux linkage by developing a magnetic North pole on the left side - this thus repels the rotating magnet. Viewing the coil 'head on' from the left, the conventional current would be flowing aNti-clockwise [see this for further clarification: kzbin.info/www/bejne/qJe7emumdriYqKc ]. As the north pole of the rotating magnet moves away from the coil, the coil tries to oppose the changing flux linkage by developing a magnetic South pole on the left side - this thus attracts the rotating magnet. Viewing the coil 'head on' from the left, the conventional current would be flowing clockwiSe. And so on.

[@lamisazamzam]

I would love to know why the current changes direction...

[@ForestLearn]

Apologies for the late reply. Glad to hear that, have you thought about it a bit yourself? Check this out for some clues (kzbin.info/www/bejne/r2PGZGmNbrabsKc), have a go at answering the qn yourself and then I'll post an answer :)

[@ForestLearn]

​ @lamisazamzam See answer in pinned post :)

[@lamisazamzam]

Thank you so much; your videos really helped me much. I sat for Edexcel International A Level Physics 6 units last October and achieved 97% marks. I followed almost all your videos and really found them helpful. Thanks again for your help.

[@ForestLearn]

@@lamisazamzam Wow, congratulations! I'm grateful to have played a small part in your success, all the best :)

[@athulakulasinghe1957]

Decrease the rate of change of flux by increasing the induced emf

[@ForestLearn]

Sorry for the late reply. Be careful - it's the rate of change of flux linkage which causes the induced emf, not the other way around. Decreasing the rate of change of flux linkage decreases the induced emf.

[@Insta_Feed]

Would you consider making a video on type 3 as i think thats the type that comes in q most of the time ?

[@ForestLearn]

Apologies for the late reply. I sure would like to!

[@ForestLearn]

@Insta_Feed Type 3 video is now up: kzbin.info/www/bejne/nXSnkmalo9B0bbc . Hope you find it useful!