Day 23 Faradays Law and Lenzs Law

At the beginning of the class, we did a review problem of finding the force and the magnetic field.

This picture shows the activity that when the two lines were charged they got closer.

We thought that there were actually forces between two wires that caused them close to each other, but because the power is alternating current, there is no force.

The graph on the left is our prediction of Magnetic Field vs. time, and the right graph is the magnetic field vs. time graph made by professor. They actually look alike.

We also used logger pro to make a graph 

On the top example, the flux is 0 because the magnetic field go through. But in the bottom example, the magnetic field actually is perpendicular to the side. So the flux is B*a*b.

This is an experiment about the magnetic field in a loop.

We collect data.

The professor demonstrated a experiment which he put a magnet through the loop and the meter would go up and down as the magnet go in or out the loop.

These are 4 ways that the strength of current is influenced.

This is another experiment when we have current from a coil and magnet.

When we put a ring of aluminum and applied current to it, the ring floated.

However, if there is a gap between the ring, it will have no effect.

Here is another activity, when dropping the magnet into the magnetic tube, it will drop slower than the non-magnetic tube.

This is a diagram of how the magnetic field and velocity of how the previous activity works.

The left graph is the graph of the flux and electromotive force. They are the same but shift a little bit. And the right picture we derived the equation of flux and electromotive force.

Conclusion

In today's class, we first reviewed a problem about force related to magnetic field, then we talked about Faraday's Law, flux through a loop, current from a coil and magnet, Lenz's law, and finally we derived the equation and drew the graph of flux in a coil as function of time and electromotive force.