5/14 week12 day 2 Lenz's Law and Faraday's law

At the beginning of the class, the professor gives us two lines, both of which have same current, and then we draw the magnetic field in both of them and find the magnetic force of each of them.
Then we know that B=u/4pi*Idl/a^2 so we get that F=u/2pia*I_0*I_1*L

Then the professor shows us the experiment. When closing the switch, and the two lines were charged, they get closer thant no charged.

Then we make a prediction, we think that because there are forces that makes them closer, but actually, beacuse of the power is alternating current, so there is no force.

Then in these two photos, the professor use logger pro to make a graph of the change of magnetic field as time changes. and we draw the north and south poles in the graph.Professor then performed the experiment by switching on the power supply causing an alternating current in the two parallel lines. There are in fact no net forces acting as there due to the alternating current. Then he uses logger pro to show magnetic field in respect to time.  Two cycles here are observed in which we can interpret the magnetic field oscillations caused by the north and south poles by applying Faraday's law

We use logger pro to collect data and make a graph in this photo,

in this photo, we caculate the flux of magnet. the first one, because the B and A are parallel, so the flux is 0, and the second one, because they are perpendicular so the flux=B*a*b

in this photo, we begin to do the experiment about the magnetic field in a loop.

we collect the data and fill the form.

in these two photo, the professor use a magnet to cross the loops and when it enter or leave the loops, the dash board will change. Professor uses a bar magnet and galvanometer and allowed the magnet to go back and forth causing movement (changing magnetic fields) which stimulates a current seen in the movement of the meter through induction. As he stops in the center of the coil there is no change in the meterwhen it stay in the loops, it doesn't change 

in this photo, we list 4 reasons that can influence the dash board.If we want to maximize the current on an induced EMF we can add more loops on the coil, have a bigger loop by increasing the area, use a bigger magnet, and also move the magnet faster

Then we use this equipment in the photo to see what will happen

in this video, when we put a loop of coppr or alaluminium on the equipment , it can suspend。

But when the loop is cut, it doesnot suspend any more

Then in this photo, we draw the graph of force, magnetic field. When the north pole of the magnet is going toward a loop, the flux increases and an upward secondary magnetic field is created causing a counterclockwise current. The changing flux created by the magnetic field created by the induced emf causes the the loop to float due to the force upward.

in this photo, we put the magnet into the magnetic tube and it will drop slower than the not magnetic tube,

in these two photos, we first find the E that created by the moving of magnet and draw the two graphs of B and E

Conclusion:

In today’s class, we learned Lenz's Law and Faraday's Law to see how we could induce a current using magnetic fields and magnetic fields, forces, torque, and flux. find that an EMF and flux explains the relationship between the two by using Lenz's law and Faraday's Law to magnetic fields. We did many experiments that made a steel ring and we saw that the forces of the magnetic field create some objects to levitate just like the rings.