Magnetic Fields and Magnetic Forces (0507)

Magnetic Fields and Magnetic Forces

In this photo, the professor put iron filings sprinkled around the magnet and we observe that there are circles from north pole to south pole

The bar was labeled N on the left and S on the right. As we observed, the magnetic fields entered the S side and exited on the N side.

On the table was a permanent magnet. Interestingly, when the magnet was taken apart into 2 separate pieces, the pieces still behaved like a magnet with north and south parts.

We imagined that the big permanent magnet was just a accumulation of many tiny magnets. Therefore, when we broke the big one into two. the pieces behaved as two separate magnets. The tiniest magnet is the atom, assumingly

The total flux of the dipole magnet is equal to poles enclosed/ constant.

We trying to find the the magnetic field, Since the field is constant, the oscilloscope only showed a single dot on the screen. 

Here we moved the magnetic bar closer to the screen in many direction. As we moving, the dot on the screen moved in different direction. We used the right hand rule if it made sense or not. The formula here is F=v cross B

Here we were trying to find the unit of B.

Here we were practicing finding the acceleration from the given information. We first found the magnetic force, since magnetic force caused the proton to move in the circle. The magnetic force was actually centripetal force. We equated qvBsintheta= ma to find a.

Right Hand Rule

Finding the r by equating the magnetic force with centripetal force.

Here we can imagine that the magnetic is in the positive j direction. Here we had to use left hand rule because the current is actually moving electrons. When the current is in negative i direction, another word, moving from right to left, The force will be up, string up. Otherwise, string would move downward.

Finding magnetic field by equating magnetic force with centripetal force. Since w= 2*pi* frequency, since r= v/w. we put that into finding B equation

We use right hand rule for proton, and left hand rule for electron.

The current was going in the counter clock wise direction. The net force would be zero in a closed loop.

The net force in the closed loop is always zero, but not the net torque.

Homework question.

Our illustration.

Summary:

     Today, in class, we learned about magnetism and its properties. We saw how the magnetic fields looks like on the magnet.  Then we learned about the right hand rule when it comes to currents and force. We also saw that current, length and magnetic field determine the force of the magnetic field. When it is given magnetic charge by being placed in a horseshoe magnet and cut into half, the magnetic charge is shown by using a compass.