Electromagnetic Induction

Measuring Inductance

We wired up a circuit according to the schematic above. We used a function generator to provide 10.00 V with an internal resistance r, of 50 ohms. A circuit with resistance 347 ohms and an inductor with internal resistance R_L and inductance L were all wired in series with the function generator. Our goal is to measure the inductance of the inductor directly, then compare it with two experimental values obtained from the physical characteristics of the inductor and from data obtained from an oscilloscope. The true inductance of the inductor was 8.22 mH.

 Here we see the inductor we used, it consisted of N = 440 turns.

We adjusted the oscilloscope to get an output that allowed us to collect our half time decay. We counted the divisions on the oscilloscope and measured the half time to be 6.67 microseconds.

From the data collected from the oscilloscope, we were able to calculate the inductance of the inductor. This value was 9.63 mH.

Now, we can calculate the inductance from the inductor's physical attributes. We measured the cross-sectional area to be A = (0.04 m)^2. The number of turns was written on the inductor, N = 440 turns. The measured length l = 0.055 m. Plugging all of this into the original formula gave us a calculated inductance of 7.08 mH.