5H30.15-Bending an Electron Beam

5h3015bending_an_electron_beam_2 5h3015bending_an_electron_beam

Video: Watch this demo

Instructor’s video

SMU Physics Demo

Description: This demonstration shows how a magnetic field can deflect a beam of electrons.


  • Crooke’s Tube
  • High voltage DC power supply
  • Bar magnet
  • 2 Banana plug cables
  • 2 Alligator clips
  • Electric Magnetizer

Setup Procedure:

  1. Using the electric magnetizer, magnetize two bar magnets.
  2. Connect the Crooke’s tube to the high voltage DC power supply.
  3. Turn on the power supply and ensure a visible electron beam appears, then turn off the power.
  4. Face the appropriate side of the crooke’s tube to the class.

Demonstration Procedure:

  1. Turn on the power supply.
  2. Bring a bar magnet near the tube to deflect the beam.
  3. If you reverse the magnet and use the other pole, note that the beam moves in the opposite direction.
  4. When finished, turn off the power supply.

High Voltage
High voltages are produced. Never touch when the power supply is on.

X-ray radiation
This device emits X-ray radiation. Avoid long exposure.