A basic lock-in amplifier experiment for the undergraduate laboratory

A basic lock-in amplifier experiment for the undergraduate laboratory

We describe a basic experiment for the undergraduate laboratory that demonstrates aspects of both the science and the art of precision electronic measurements. The essence of the experiment is to measure the resistance of a small length of brass wire to high accuracy using a simple voltage divider and a lock-in amplifier. By performing the measurement at different frequencies and different driv...

A Simple Low-Cost Lock-In Amplifier for the Laboratory

www.JCE.DivCHED.org • Vol. 82 No. 9 September 2005 • Journal of Chemical Education 1399 Efforts to modernize physical and analytical chemistry teaching laboratories are often hampered by a lack of funds, but it is possible for students, as part of their laboratory course or for advanced projects, to construct scientific instrumentation that can subsequently be used in experiments. Examples incl...

A Pulse NMR experiment for an undergraduate physics laboratory

Using a Lock-In Amplifier

In this lab, we explore the principles of the use of a lock-in amplifier, using a He-Ne laser, light chopper, and a photodiode as the lock-in input. We explain and use the concepts of phase sensitive detection, dynamic reserve, and time constants to determine both the range of linearity of the photodiode in use, as well as the frequency response of the photodiode. Furthermore, we determine whet...

An undergraduate laboratory experiment on quantized conductance in nanocontacts

We describe an undergraduate laboratory experiment on conductance steps observed to occur near integer multiples of 2e/h as nanocontacts form and break between gold wires in loose contact. This experimental arrangement was first described by Costa-Krämer et al. @Surf. Sci. 342, L1144 ~1995!#. A simple op-amp circuit in conjunction with an inexpensive storage oscilloscope suffice to observe the ...