Objectives of the Experiment
● To record a Franck-Hertz curve for argon.
● To measure the discontinuous energy emission of free electrons by inelastic collision.
● To interpret the measurement results as representing discrete energy absorption by argon atoms.
● To measure the Planck's constant h.

How it works
When an electron whose speed is zero has an inelastic collision with an argon atom, the kinetic energy is lost to the atom and causes one of the outer orbital electrons to be pushed up to the next higher energy level (E2). This excited electron will within a very short time fall back into the ground state level (E1), emitting energy in the form of photons. The energy is e•U0=E2-E1=h•ν. If the first excitation electric potential of the argon atom is U0, then we can obtain the Planck's constant h=λe•U0/c.

Features
● High sensitivity and stable current amplifier is used.
● Ar-tube is fitted in a metal enclosure which has a transparent synthetic glass window, allows good visualization.

Typical Result
    

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