4. "Can you explain the properties of Lenz's law and how it affects flux?"
Actually, Lenz's law does not affect flux in the sense that it doesn't change it. But it does tell us what happens when there is a change in flux, for whatever reason. Faraday's law tells us that whenever there is a change in flux, an emf is produced. And if that emf is generated in a conducting material then a current will be produced (referred to as the induced current). Lenz's law tells us about the direction of the induced emf and induced current in a circuit. The law states that:
I know it sounds vague but let me explain an example from class. (You can also look at [3] above.)
Think of pulling a small metal sheet out of a magnetic field, as shown above. When the sheet is in the field there is magnetic flux passing through it. If you move the sheet around but don't actually move it out of the field nor twist it the flux through the sheet does not change. That's because the product B.A remains constant even though you move the sheet around. However, if you start to move the sheet out of the field, the flux through the sheet does change; clearly, it gets smaller as the area of the sheet in the field gets smaller. Faraday's law tells us that since the flux is changing an emf must be produced in the sheet. And since the sheet is a conductor, the emf will produce a current. But what is the direction of the current? That's where Lenz's law comes into play ... the direction of the induced current will be such that it opposes the change.
So, what's producing the change? ... the motion of the sheet out of the field. Consequently, according to Lenz's law, the induced current will try to "resist" the motion out of the field! That means the induced current will have to be clockwise, as shown. That's because the left hand end of the sheet, which is still in the field, must experience a force to the left as the sheet moves to the right; it's a bit like a frictional force. That will be achieved by a current moving in the direction shown. Because the size of the emf (and hence, current) is determined by the rate the flux changes - Faraday's law - the faster the sheet is moving, the greater the emf and current and the greater the resisting force! If the current were moving in the opposite direction, the force would be directed to the right and in contradiction to Lenz's law, because the induced current would then be "helping" to change the flux not opposing it.
If the sheet was made of some insulating material like plastic or glass, there would still be an emf induced in the sheet but no induced current (because its electrical resistance is so great). As a result there would be no opposing force, since i = 0. So it is "easier" to pull an insulating sheet from a magnetic field than a conducting sheet!
Lenz's law involves a good deal of conceptual understanding that only comes with trying examples and analyzing particular cases. Therefore, I would encourage you to read through the brain "busters" on magnetic induction.
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