May 15 1015

In left and right side of a wire that has current pass through, the direction of magnetic field is opposite. We can find the direction by righ hand rule. At this point, we draw the magnetic force applied on the wire to determine their motion.

We perform the experiment to prove our prediction is correct. They attract each other, which matches our prediction.

Later, we write the expression of magnetic on each wire due to the magnetic field cause by the other wire.

We discussed about magnetic field produced by an AC current. Since the direction is changing all the time, so the magnetic field is reversing all the time. As a result, there is no magnetic field in an AC current.

An experiment to record magnetic produced by the current. There is a new equipment that is applied here to detect the magnetic field. We graph he magnetic field respect to time axis, and we got a trig function graph.

In our group we perform same experiment to observe the relationship between number of loops and magnetic field. We predict that the more loops we have, the larger magnetic field at that poiont.

When we record data by logo pro and graph it, the graph generally matches our prediction. after 3 loops, the graph is more linear. We believe that for loop 1 and loop 2 the graph is less linear because we didn't wait for the magnetic go to completely stable to record it.

We draw the magnetic flux through the closed surface. This practice tells us that when we do the cross product, the area vector is vector normal to the surface, not the surface itself.

Not only electric can produce magnet, magnet can also produce electric. This experiment shows that a closed loop moving in a magnetic field causing its flux will produce electric.

Since both magnetic and electric can produce each other. When we put steal ring in it, the motion of the steal in the magnetic whhich produced by the current cause current in the steal ring, and it also produce magnetic field, which cause the motion of the steal ring. If we put some other ring that is non conductive or it is not complete that can't form a closed surface, nothing will happen.

One is Al and the other is glass. if we drop a nonconductive cylinder in the al and magnet cylinder in the glass, they will fall at the same time due to free fall. What is more, they didn't produce current and magnetic field.

This time, the magnet cylinder drop from the al tune is much slower. cause during its fall, it caused flux change which produce current, and current produce magnetic field. Due to the magnetic force, it falls much slower

In this graph, we draw the magnetic and force applied in each tunnel, and we write the flux change in the al tunnel. The reason that magnetic produce electric, and caused emf is when the flux change in the system.

We draw the graph of emf and magnetic field change respect to time. they are both trig function. The reason that the graph looke like this is beacuse during the motion, angle between field and surface changes. Since we applied dot product to determine flux, the change of flux also contains trig function.

Summarize: Magnetic can produce electric due to the change of flux in the field and motion of the wire loop. The emf caused by this is change during the spining of the loop. Electric can also produce magnetic field. Thus, when we do problems that contains both magnetic and electric, we need to consisder both the magnetic force and emf due to their relationship.