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Benefits

• Fascinating Nobel Prize experiment (Franck-Hertz 1925)

• Suitable for demonstration and lab courses as well
• Compact argon tube in sturdy casing - ready to use due to short heat-up time
• Control unit compatible to Ar and Hg tube
• Easy-to-use software for control, data acquisition and evaluation

Learning objectives

• Energy quantum
• Quantum leap
• Electron collision
• Excitation energy

Principle

Electrons are accelerated in a tube filled with argon vapour. The excitation energy of argon is determined from the distance between the equidistant minima of the electron current in a variable opposing electric field.

Tasks

1. To record the counter current strength I in a Franck-Hertz tube as a function of the anode voltage U.
2. To determine the excitation energy E from the positions of the current strength minima or maxima by difference formation.