Physics 1122
Experiment 7
Name_________________________________
Pre Lab
Instructor name _________________________
1. (a) State Faraday’s law and Lenz’s law. (b) If a magnetic field points into the
page and is increasing in magnitude, what is the direction of the induced current
in the wire loop shown?
2. (a) Using Eq. (2) in the laboratory manual as a guide, state three ways to change the magnetic
flux. (b) Take the derivative of the flux, and identify the mathematical term that corresponds to
each of your answers in Part (a).
3. A copper disk swings like simple pendulum in and out of a
magnetic field, as shown in the figure. Make a sketch of the
amplitude of the oscillations vs. time; assume there is no air
resistance. Explain any changes to the amplitude.
4. A ball and a magnet are released simultaneously from the same height.
They both fall vertically but, on its way down, the magnet passes through
a coil. Which one reaches the ground first? Explain.
5. Suppose a student recorded the following data during Step 10 of this experiment,
A
6.20 deg
4.70 deg
3.20 deg
2.40 deg
1.80 deg
Time
2.00 s
4.00 s
6.00 s
8.00 s
10.0 s
The student was careful to start taking data when the angular position of the pendulum was zero.
Unfortunately he does not have a computer available to fit the data as you will in Step 12, but he
knows that the amplitude of oscillations decays exponentially according to
,
where C = 0. Use the data obtained by the student to plot a straight line graph of the appropriate
variables on the graph paper, and use it to find values for the parameters A0 and B.