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Franck-Hertz Apparatus
Franck-Hertz Apparatus

Franck-Hertz Apparatus
Our Price: $2,922.00

Availability: See Product Text For Shipping Time
Product Code: 2482

Description Technical Specs
PLEASE NOTE: Advanced Physics Equipment is built-upon-order. We do not stock these items in house, but order them built when an order is placed. Build orders take approximately 90 days.
  • Uses Argon for Room Temperature Measurements
  • View on Oscilloscope or Record Manually for Quantitative Work
  • Compact Unit for Easy Setup

In the Franck-Hertz experiment electrons in a vacuum tube containing a small amount of vapor are accelerated towards an anode grid. Beyond the grid is a second electrode held at a small negative potential with respect to the anode, so that only electrons with a certain minimum energy can reach the second electrode. The current arriving at this electrode is monitored as the accelerating voltage is increased.The schematic shows the arrangement. In general, the current rises with the accelerating voltage, but a series of superposed decreases is also observed as electrons acquire enough energy to excite atoms of the vapor. The energy lost in the excitation leaves the electron with too little energy to reach the second electrode. From the spacing of the successive minima, the ionization potential of the vapor atoms can be derived. The original apparatus used mercury vapor heated to 180C. This apparatus uses argon at room temperature, which is much easier to control, and up to five minima can be easily obtained with manual plotting. The argon tube is enclosed in the metal casing of the unit, which also shields it from stray environmental voltages.

The Franck-Hertz Apparatus can be used alone for manual recording of the voltage-current reserves or with an oscilloscope (not included) in XY mode for repeated sweeping of the accelerating voltage. The built-in panel meters indicate the current and the three tube voltages. The current amplifier has four ranges from 10^-5A to 10^-8 A for full scale deflection. A switch allows the voltages on the control grid, the anode, and the reverse bias electrode to be monitored in turn. Includes full operator's manual.

Download the instruction manual for the Franck-Hertz Apparatus. (.pdf file, 373K).

Set of equipment used for observing the excitation transition of electrons in Argon. Compact unit includes Argon tube, power supplies, and amplifier in one box. Oscilloscope required (not included).

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