Relativistic Electron Experiment for the Undergraduate Laboratory

TL;DR

This paper presents an undergraduate experiment that measures relativistic electron momentum and kinetic energy, demonstrating relativistic effects and enabling the calculation of fundamental constants.

Contribution

It introduces a practical laboratory setup for independent relativistic electron measurements suitable for undergraduate education.

Findings

Relativistic electrons exhibit predicted energy-momentum relationship

Accurate electron rest mass and speed of light values obtained

Experimental data confirms relativistic physics principles

Abstract

We have developed an undergraduate laboratory experiment to make independent measurements of the momentum and kinetic energy of relativistic electrons from a \beta -source. The momentum measurements are made with a magnetic spectrometer and a silicon surface-barrier detector is used to measure the kinetic energy. A plot of the kinetic energy as a function of momentum compared to the classical and relativistic predictions clearly shows the relativistic nature of the electrons. Accurate values for the rest mass of the electron and the speed of light are also extracted from the data.