Precision electrical measurement experiment using a lock-in amplifier that is suitable for science and engineering undergraduates

Despite the lock-in amplifier's being one of the most frequently used precision measurement instruments in science and engineering, most undergraduates students in physics know very little about the lock-in detection technique and never get a chance to experience or learn about the beauty of precision measurements. In this article, an introductory-level electrical experiment using a lock-in amplifier and designed for upper-level undergraduate science and engineering students is described. In the presented experiment, students measure the resistance of a small piece of copper wire, a piece that is often too small to be accurately measured with a multimeter, and calculate the resistivity of copper. As additional topics for discussion, the effects of 1/f noise on measurement uncertainties can be demonstrated with a lock-in amplifier, and AC impedance measurements for capacitors or inductors are equally possible when using the same setup.