Improving student understanding of lock-in amplifiers

The lock-in amplifier is a versatile instrument frequently used in physics research. We find that students tend to struggle with its basic operating principles, leading to a variety of difficulties. To improve their understanding, we have developed a research-based tutorial that makes use of a computer simulated lock-in amplifier. The tutorial allows students to realize their conceptual difficulties by comparing their predictions with the outcome of the simulations, hopefully leading them to a better understanding of the process of lock-in amplification. (C) 2016 American Association of Physics Teachers.