Day 91: Electromagnetic Induction Paradigm Lab

Today, we started investigating electromagnetic induction in AP Physics 2. I demonstrated how inserting a magnetic into a solenoid resulted in a current in the solenoid that could be measured with a galvanometer. We then discussed as a class what variables may affect this induced current. The students thought of enough variables such that each of the six groups qualitatively investigated a different variable. After investigation, each group demonstrated their investigation and shared their results with the rest of the class.

5 thoughts on “Day 91: Electromagnetic Induction Paradigm Lab”

1. Andy "SuperFly" Rundquist says:

I really love induction, but I think that you have to be careful calling it induction when you move the coils instead. Then it’s “just” motional emf. I tried to really hold my students to that distinction this year, but I’m not sure how successful I was.

2. I don’t think I appreciate the distinction in this case. I think a conductor moving through a magnetic field would be an example of motional emf. How is electromagnetic induction defined? Is it appropriate to use that term whenever there is a change in magnetic flux that induces an emf? If so, would inserting a magnetic into a solenoid qualify?

1. Andy "SuperFly" Rundquist says:

If B is changing, you get a new kind of E field (one that has a curl) and that pushes the charges around. If B is fixed (like in the case of the coil moving but not the magnet) then it’s “just” motional emf where the mag force is pushing the charges around. The first is induction, the second is just magnetic forces.

1. I see how for a uniform B field, it would be just motional emf. However, when a permanent magnet is inserted or removed from a solenoid, doesn’t that result in B changing within the solenoid? Would the back emf produced in a motor qualify as induction?

1. Andy "SuperFly" Rundquist says:

yep, as long as the magnet moves, then you’re in business with induction. However, take the example of the paperclip generator (the opposite of the paperclip motor). The magnet just sits there and the coils turn. That’s not induction.