Lenz's Law

[EspoirTron]

I have just completed studying Lenz's law and what I was wondering was, what types of questions could we expect on a VCAA paper in relation to Lenz's Law, would it strictly pertain the direction in which the induced current would flow?

[BigAl]

yes..definitely expect a question about Lenz's law...I learned this law's interpretation  not throughout the term but one day before the exam You'll probably be given a circuit with magnets and stuff..Moving the coil through the magnetic field will induce some force...Wait..This opposes one of the fundamental things in physics..You can't just create something out of nowhere..nature wont allow this...So you need to apply one of the nature's laws  

[götze]

Kebab your already up to lenz law were still doing the right hand screw rule and stuff. Btw do you use the  heniman physics book ?

[SocialRhubarb]

Seeing that Lenz's law applies to the direction of currents induced by magnetic fields, I'd say yes, it would pertain to the direction in which the induced current would flow.

For example, if you moved the north pole of a magnet through a loop of wire from above, in which direction would the induced current flow as the north pole approaches when viewed from above? Explain your answer using Lenz's law.

Spoiler

As the north pole approaches, the change in flux induces a current. Lenz's law states that the current induced will oppose the change in magnetic flux which induced the current. The magnetic field is increasing in a downward direction, thus the current induced will generate a magnetic field pointing upwards, towards the magnet. Using the right hand solenoid rule, an anticlockwise current is induced to produce a magnetic field opposing the change in flux.

Alternatively, it is possible to think of the problem in terms of inducing a magnetic field which pushes away the magnet. For example, generating a north pole to repel the north pole approaching.

[EspoirTron]

Seeing that Lenz's law applies to the direction of currents induced by magnetic fields, I'd say yes, it would pertain to the direction in which the induced current would flow.

For example, if you moved the north pole of a magnet through a loop of wire from above, in which direction would the induced current flow as the north pole approaches when viewed from above? Explain your answer using Lenz's law.

Spoiler

As the north pole approaches, the change in flux induces a current. Lenz's law states that the current induced will oppose the change in magnetic flux which induced the current. The magnetic field is increasing in a downward direction, thus the current induced will generate a magnetic field pointing upwards, towards the magnet. Using the right hand solenoid rule, an anticlockwise current is induced to produce a magnetic field opposing the change in flux.

Alternatively, it is possible to think of the problem in terms of inducing a magnetic field which pushes away the magnet. For example, generating a north pole to repel the north pole approaching.

Thanks for that , I appreciate that and that is an excellent example.

yes..definitely expect a question about Lenz's law...I learned this law's interpretation  not throughout the term but one day before the exam You'll probably be given a circuit with magnets and stuff..Moving the coil through the magnetic field will induce some force...Wait..This opposes one of the fundamental things in physics..You can't just create something out of nowhere..nature wont allow this...So you need to apply one of the nature's laws  

Okay wait let me guess, Newton's third law, every force has an equal and opposite force? I would think that as the induced current will favour the direction that causes the flux to oppose the change, either decreasing or increasing. I got my head around Lenz's Law by thinking of Le Chatleir's principle from Chemistry, I know that may be a different way to think of it, but the whole idea of the system wanting to oppose the flux change reminded me of Le Chatlier's principle.

Kebab your already up to lenz law were still doing the right hand screw rule and stuff. Btw do you use the  heniman physics book ?

Oh yes, we just wrapped up the fundamentals of magnetism before the term concluded. I do use the Heniman physcis book, it has some interesting examples but I don't think it goes into a great deal of depth in some areas. Sometimes I feel that half of the explanation is background information on discoveries and then it flows into the actual topic; nonetheless, the book still has great explanations. The books explanations for Unit 3, Area Of Study two were pretty detailed, I found and offered excellent information, especially on amplifiers.

[BigAl]

Okay wait let me guess, Newton's third law, every force has an equal and opposite force? I would think that as the induced current will favour the direction that causes the flux to oppose the change, either decreasing or increasing. I got my head around Lenz's Law by thinking of Le Chatleir's principle from Chemistry, I know that may be a different way to think of it, but the whole idea of the system wanting to oppose the flux change reminded me of Le Chatlier's principle.

I think of newton's third law...That was the only way I got it..

[EspoirTron]

I think of newton's third law...That was the only way I got it..

Newton's third law and Le Chatlier's principle have helped me understand Lenz's law!

[götze]

Kebab are you serious about the book. Im tossing up between burning it or using it as a tissue paper. The book is so bad i just use jacks notes way more clear and easier to understand

[EspoirTron]

Kebab are you serious about the book. Im tossing up between burning it or using it as a tissue paper. The book is so bad i just use jacks notes way more clear and easier to understand

The book has its moments. I agree that the book is mostly not clear with its explanations, however it has its glimmers of hope. In total the book is quite horrendous in it explanations and examples. For the most part the questions aren't that great either, the examination-style questions are okay, but for the most part, I don't really like the questions. Doing questions from checkpoints and examination papers are a much better way to understand the theory and how to apply it in calculations. Interesting book, nonetheless, they really need to work on the clarity of their message though, Lenz's Law was not really explained well, yet again essentially of all electromagnetism and the fundamentals of magnetism were explained poorly in my opinion.