Crooke's Tube Cathode Ray Tube (Rosalyn Montgomery)

Author

Rosalyn Montgomery, Emerson Community Charter Middle School

Principles

This tool helps to reinforce the Atomic Theory of Matter. All matter is made of atoms and atoms are made of electron, protons, and neutrons.

Standards

PS1.A The sub-atomic structural model and interactions between electric charges at the atomic scale can be used to explain the structure and interactions of matter, including chemical reactions and nuclear processes.

Materials needed

Cathode Ray Tube

Power Source

Magnet

Procedure

Touch the metal tipped end of the tube with a Tesla coil as a power source.

Observe the wheel in the tube turn as the ray of electrons hit the fan wheel.

Hold a strong magnet near the tube and use it to bend the stream of electrons.

Explanation

The Crooke's Tube and Cathode Ray tube were used to discover the presence of a charged particle in atoms, specifically the electron. Recreating the original experiment can provide a concrete visual for the students to help them understand the atomic theory, which can be quite abstract.

Questions

Why does the wheel turn when the electricity is applied?
Why does the light ray bend when it is near a magnet?
Imagine that you are JJ Thomson, in your own words, explain what you observed as an explanation for the presence of electrons.

Everyday examples of the principles illustrated

Any glowing Neon Sign or old tube televisions are descendants of the Crooke's tubes and Cathode ray tubes.

Photos