LAUSR

We present a durable and inexpensive construction of a Johnson noise experiment suitable for advanced undergraduate students. By measuring the root-mean-square voltage noises for different resistors and taking into account the input capacitance of the amplifier circuit, we demonstrate that the experimental setup is capable of measuring the value of the Boltzmann's constant to be J K−1. The setup also allows us to determine the capacitance of an RG-58/U cable to be 80 ± 3 pF m−1. We also provide observations from two years of teaching this experiment, containing common student pitfalls. Finally, we discuss possible adjustments of the experiment according to a time constraint.