Procedure:

The circuit diagram above shows the general set up for the experiment. Measure the following things: $V_s, V_r, V_{source}, V_p,$ along with the physical dimensions of the secondary coil, $A_s, \: l_s$, respectively, where these are, the amplitudes of the secondary voltage, resistor voltage (voltage across the resistor), frequency generator source voltage, primary coil voltage, area and lenght of the secondary coil. You will need to know that the number of windings of wire comprising the primary coil, $N_p$, and the number of turns of wire for the secondary, $N_s$, are 570 and 277, respectively. So, how to measure these things?

A function generator is connected in series with the primary coil and a resistor. The secondary coil should be inserted in the primary coil in a concentric position. The voltage across the secondary can be directly measured by the oscilloscope. The resistance should be somewhere between 500 to 1000 $\Omega$. The current through the primary coil may be found by measuring the sinusoidally varying voltage across the resistor and dividing by the resistance. At some point in the lab one must measure the voltage across the primary coil, and this will require some caution so as not to short out the resistor. Let me explain.

If we could simply put the leads from the oscilloscope anywhere we wished to make a measurement, without worry of fundamentally changing the circuit we are examining, then life would be nice. But we can't. One must arrange the circuit we examine so that the circuit element whose voltage we measure should be grounded on one side. That way, when we attach the clip leads from the scope, no circuit elements would be ``shorted out'' by the scope ground. The principle is this: the scope ground must be attached to the circuit ground. If we tried to measure the voltage across the coil (in series with the resistor, as in the figure above), and attached the scope ground at the node between the coil and resistor, then the resistor would be shorted out of the circuit completely, radically altering the amount of current flowing in the circuit. So, take heed, and swap the order of the circuit elements to accommodate the measurement one is trying to do!

Take the following data sets:

1. for each new frequency (10 different frequencies, between 500Hz and 5 kHz), measure $V_R, V_s,$ and $V_{source}$, where the subscripts refer to the resistor, and the secondary and primary coils, respectively. Make a table of your results, with an extra column for the calculated current.
2. for one frequency, sketch an accurate waveform for $I(t), V_s(t)$, and $V_p(t)$, just as they look on the scope, being very careful to maintain the correct phase relations between the waveforms. This data set will be useful for discerning the effects of Lenz's Law.

In order to calculate the induced EMF one must of course calculate the cross sectional area of the secondary coil and know its length, and the number of turns of wire for both the secondary and the primary coils. The number of turns of wire which forms the secondary coil will be counted by the student (the number varies a bit from coil to coil). The primary coil is a rather thick thing with a few layers of windings. This actually makes its magnetic field less straight forward to calculate, but it may be modeled as a simple solenoid with a given number of windings. Consult your instructor for the effective number of windings for the primary coil.