Day 21 Magnetic Forces and Fields

At the beginning the of class, we have a bar magnet and a small compass. We need to draw which way the compass points when moving the compass around the magnet. The arrows leave from north pole and direct to south pole.

This shows all arrows together.

The professor put iron sprinkled around the magnet and we observe that the picture is like what we drew.

In this picture, we draw three loops, which are the loops contain one pole, both poles, and no pole. The number is how many arrow in and out the circles.

This is the large magnet that the professor rub a wire on to make the wire a magnet. 

We used the equation to find magnetic flux

We found that magnetic net flux is always 0

The professor shows us that when we put magnet next to the oscilloscope, the point on the oscilloscope will go different direction as the magnet moves.

In this activity of magnetic forces on moving charges, we found out two vectors of points.

We used the equation F = q*v*B to find the unit of B.

In this activity of using Lorentz Force in calculation, we found the magnitude and direction of the force exerted on the proton by the magnetic field.

By the equation F=q*v*B, we calculation the Force, and acceleration.

Also, by applying centripetal force, we can calculate the radius.

We also did a problem and used the equation r= mv/qB and v = 2πrf to find B.

In this activity, the professor put a wire between the magnet and connect to the battery. We observed that the wire will move up and down depends on the charges.

In this activity, we answer 4 questions on the lab manual.

                                    a. v = L/t

                                    b. I = q/t 

                                    c. F = qvB = ILB

                                    d. dF = IdLB

Then, we did an experiment called magnetic force on a current loop.  

We need to found the direction of the magnetic field and the direction force.

Then the professor performed the experiment and showed us that the loop will spin up 90° 

Conclusion

For today's class, we learned about magnetic forces and magnetic field. We first looked at how the arrow of compass would turn near a magnetic and then did a lot of activities about magnetic forces, magnetic field, Lorentz Force on a current loop.