A robust experimental setup for Johnson noise measurement suitable for advanced undergraduate students

Abstract

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.

Determination of absolute zero temperature from thermistor voltage noise

“…We use epoxy (not shown in the diagram) to fix the thermistor in place and also to improve thermal conductance. The two terminals of the thermistor are then wired to a grounded BNC connector which is eventually connected to either an amplifier (described in [10]) for voltage noise measurement or an ohmmeter (Fluke 115) for temperature measurement 1 , as described in figure 2. The aluminum box also acts as a shield for external electrical noise that might interfere with the measurement.…”

Set-up for observation thermal voltage noise and determination of absolute temperature and Boltzmann constant

“…Study of electric fluctuations is for decades important laboratory work in good universities, for instance references [2,[10][11][12][13][14][15][16][17][18][19], however all those set-ups are difficult to be reproduced or require expensive commercial electronics. The purpose of the present work is to describe and innovation of teaching of electrical noise with a set-up which can be easily reproduced within one week in every school.…”

Set-up for observation thermal voltage noise and determination of absolute temperature and Boltzmann constant

“…Study of electric fluctuations is for decades important laboratory work in good universities, for instance Refs. [2,[10][11][12][13][14][15][16][17][18][19], however all those set-ups are difficult to be reproduced or require expensive commercial electronics. The purpose of the present work is to describe and innovation of teaching of electrical noise with a set-up which can be easily reproduced within one week in every school.…”