Measuring the balance of the world's largest machine

10.1119/10.0005989.1 The electrical power grid has been described as the largest machine in the world. Although we customarily assume our electrical outlets provide a steady sinusoidal voltage with a frequency of 60 Hz (in North America), the variations from that ideal are easy to observe using the methods described in this article. These frequency variations are important since, as can be shown with introductory-level physics concepts, they arise when power generation and usage are not balanced on the electrical grid. The challenge of balancing the electrical grid will increase over the coming years as we adopt more sustainable but less predictable energy sources, and this connection to one of our current societal challenges makes this project interesting to students.