Physics307L:People/Cordova/Matt's e/m Ratio Summary

My partner for this lab was Sebastian.
The notebook for this lab can be found here.

Purpose

The purpose of this lab is to obtain the e/m (or the charge to mass) ratio of an electron. This will be done by measuring the radius of curvature of a beam of electrons traveling in a magnetic field.

Safety

• A high voltage source is in use.
• This lab is done primarily in a dimly lit room. Be aware of your surroundings.

Equipment

• e/m Experimental Apparatus, composed of a tube of dilute helium gas, an electron heater, focusing magnets, and a Helmholtz coil used to provide a constant magnetic field
  • This description is from Brian Josey's lab notebook
• SOAR DC Power Supply Model PS-3630 (Electron Gun Heater)
• Gelman Instrument Company: Deluxe Regulated Power Supply
• Hewlett Packard 6384A DC Power Supply (Helmholtz Coils)
• Multiple BNC cables
• 3 voltmeters (one of which was used as an ammeter)

Set Up

A detailed set up can be found in Prof. Gold's lab manual. Basically, a power source is attached to the Helmholtz coils in order to create a magnetic field. Another (separate) power supply is attached to the electron gun. Use voltmeters to achieve a more accurate reading on the voltage/amperage being applied to the apparatus.

• Note: If the electron beam bends downwards instead of forming a circle, simply flip how the electron gun is attached to the power supply.