Franck - Hertz experiment

In summary, in the experiment, it was found that the minimum value of anode current occurs periodically and is known as excitation potential energy when multiplied by the period and e. However, the connection between this periodicity and the quantization of energy levels in atoms is not clear. According to the wiki article, this periodicity may be due to resonance and the absorption of energy at a specific value (4.9 electron volts). Electrons that collide with mercury atoms can only lose this specific amount of kinetic energy, regardless of their initial speed. Slower electrons do not lose any significant energy, while faster ones do not lose all of their energy upon collision.
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In the experiment, it is observed that the minimum value of anode current occurs periodically and its period multiplied with e is known as excitation potential energy.

I don't see the link between this periodicity and quantisation of energy levels of atom.
Could anyone please make this clear?
 

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Pushoam said:
View attachment 230823

In the experiment, it is observed that the minimum value of anode current occurs periodically and its period multiplied with e is known as excitation potential energy.

I don't see the link between this periodicity and quantisation of energy levels of atom.
Could anyone please make this clear?
From the wiki article.
It seems the periodicity is a resonance.When the KE is near a multiple of the 4.9eV energy then absorption is more likely.

They discovered that, when an electron collided with a mercury atom, it could lose only a specific quantity (4.9 electron volts) of its kinetic energy before flying away.[4] This energy loss corresponds to decelerating the electron from a speed of about 1.3 million meters per second to zero.[5] A faster electron does not decelerate completely after a collision, but loses precisely the same amount of its kinetic energy. Slower electrons merely bounce off mercury atoms without losing any significant speed or kinetic energy.
 

1. What is the Franck-Hertz experiment?

The Franck-Hertz experiment is a classic physics experiment that was conducted in 1914 by James Franck and Gustav Hertz to demonstrate the quantization of atomic energy levels. It involves passing electrons through a gas-filled tube and measuring their energy after collisions with gas molecules.

2. What is the significance of the Franck-Hertz experiment?

The Franck-Hertz experiment provided evidence for the existence of quantized energy levels in atoms, which was a key concept in the development of quantum mechanics. It also helped to confirm the Bohr model of the atom and contributed to the understanding of electron behavior in gases.

3. How does the Franck-Hertz experiment work?

In the Franck-Hertz experiment, electrons are emitted from a heated cathode and accelerated towards a positively charged anode. The electrons then pass through a gas-filled tube, where they collide with gas molecules and lose energy. The energy of the electrons is measured by a collector electrode, which records a decrease in current when the electrons have lost enough energy to no longer reach the collector.

4. What is the purpose of the collector electrode in the Franck-Hertz experiment?

The collector electrode in the Franck-Hertz experiment is used to measure the energy of the electrons after they have passed through the gas-filled tube. By measuring the decrease in current as the electrons lose energy, researchers can determine the energy levels of the gas atoms and confirm the quantization of energy.

5. How did the Franck-Hertz experiment contribute to the development of quantum mechanics?

The Franck-Hertz experiment provided concrete evidence for the quantization of energy levels in atoms, which was a key concept in the development of quantum mechanics. It also helped to confirm the Bohr model of the atom and contributed to the understanding of electron behavior in gases, ultimately leading to a deeper understanding of the behavior of matter at the atomic level.

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