Franck-Hertz experiment with a Hg-tube

Principle

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

Benefits

• Experience the essence of the Nobel Price: Franck, Hertz (1925)
• Classical Version with Mercury (Hg) 
• One operating unit for 2 experiments (Hg, Ne)
• Precise determination of electron excitation energy of Hg
• Direct connection to computer, no extra interface necessary

 Tasks

1. To record the countercurrent strength Ι 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.

Learning objectives

• Energy quantum
• Electron collision
• Excitation energy