# Magnetism Learning Goals Fa13

This was our last full unit in Physics 2. I was in a hurry to get these learning goals written and posted for students so this unit is currently missing the General Skills and Experiential Value goals.

Unit 2 on electrostatics was fairly math heavy and we were short on time so I did not do anything with Biot-Savart or Ampere’s laws in this unit. I remember using those laws in my intermediate E&M course (when I was a student) but I can’t remember if we did anything with them in my intro course.

**Content Learning Goals**

1. Apply Right Hand Rules (RHRs) for the force a magnetic field exerts on a moving charge, the force a magnetic field exerts on a current-carrying wire, the magnetic field produced by a straight current-carrying wire, and the magnetic field produced by a solenoid or loop of current-carrying wire. The student can use the RHRs to determine the direction of any quantity represented in the rule. (Ex. Given directions for velocity and force as well as the sign of the charge student could determine the direction of the magnetic field exerting the force.)

2. Use the equations **$F=q(v\times B)$** and **$F=L(I\times B)$** to relate these quantities mathematically. The student can apply this equation when given magnitudes and directions for each vector as well as when given the x, y, and z components of each vector. The student can also add together multiple forces vectorially to determine the net force exerted on an object.

3. Use the equations **$B=\mu_0 I/2\pi r$ and $B=\mu_0 nI$** to calculate the magnetic fields due to a long straight current-carrying wire and a long solenoid, respectively. The student can also add together multiple magnetic fields (or forces) vectorially to determine the net magnetic field at a given location.

4. Apply RHRs to each side of a current-carrying loop of wire to determine whether an external magnetic field will cause the loop to begin rotating, and if so in what direction. The student can also use the previously mentioned equations as well as the definition of torque to calculate the magnitude of the torque exerted on a loop.

5. Relate the above equations to uniform circular motion to determine things such as the radius of the circle a charge will move in and the period of rotation (i.e. the time required to complete one trip around the circle).

6. Explain why the magnetic field is incapable of doing work and what this implies for the way a magnetic field can affect a particle’s motion and its energy.

7. Calculate the magnetic moment of a loop of current and use the magnetic moment to calculate the torque an external magnetic field exerts on the loop.

8. Calculate the magnetic flux passing through a loop or surface. (This is really just a precursor to the next goal.)

9. Use Faraday’s Law to calculate induced voltage and Lenz’s law to determine the direction of the induced current. The student can also use Ohm’s Law to determine the magnitude of the current associated with the induced voltage.

10. Use Faraday’s Law to explain the operation of electric generators.

11. Explain similarities and differences between electric generators and electric motors.

**Post Exam Topics: (Not on Exam 3 but on final exam)**

1. RC Circuits

2. Ohm’s Law, power, and impedance for AC circuits

3. Conceptual understanding of LRC circuits