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Questions and Answers
Who discovered the electron through the Cathode ray discharge tube experiment?
Who discovered the electron through the Cathode ray discharge tube experiment?
What happens when the pressure inside the cathode ray tube is reduced to 0.01 mm Hg?
What happens when the pressure inside the cathode ray tube is reduced to 0.01 mm Hg?
What is the name given to the rays that start from the cathode and move away from it in straight lines?
What is the name given to the rays that start from the cathode and move away from it in straight lines?
What material is used to coat the tube behind the anode to check the cathode rays?
What material is used to coat the tube behind the anode to check the cathode rays?
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At what pressure does a dark space appear near the cathode inside the cathode ray tube?
At what pressure does a dark space appear near the cathode inside the cathode ray tube?
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What happens when a very high voltage (about 10,000 volts) is applied between the two electrodes at normal pressure?
What happens when a very high voltage (about 10,000 volts) is applied between the two electrodes at normal pressure?
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What can be observed with the help of fluorescent or phosphorescent materials?
What can be observed with the help of fluorescent or phosphorescent materials?
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What happens to the cathode rays in the presence of an electric or magnetic field?
What happens to the cathode rays in the presence of an electric or magnetic field?
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What do cathode rays consist of?
What do cathode rays consist of?
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What do cathode rays (electrons) possess?
What do cathode rays (electrons) possess?
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What is the charge to mass (e/me) ratio of electron?
What is the charge to mass (e/me) ratio of electron?
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How did R.A. Millikan determine the charge on the electrons?
How did R.A. Millikan determine the charge on the electrons?
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Who modified the discharge tube experiment by perforating the cathode?
Who modified the discharge tube experiment by perforating the cathode?
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What is emitted behind the perforated cathode according to E. Goldstein's experiment?
What is emitted behind the perforated cathode according to E. Goldstein's experiment?
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What happens when high voltage is applied between the two electrodes at normal pressure?
What happens when high voltage is applied between the two electrodes at normal pressure?
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What do cathode rays possess that allows them to do mechanical work?
What do cathode rays possess that allows them to do mechanical work?
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Study Notes
Discovery of the Electron
- The electron was discovered by J.J. Thomson through the cathode ray discharge tube experiment.
Cathode Ray Tube Pressure Reduction
- Upon reducing the pressure inside the cathode ray tube to 0.01 mm Hg, cathode rays become visible, but the signal strength decreases.
Cathode Rays
- Rays emanating from the cathode and traveling in straight lines are referred to as cathode rays.
Anode Coating Material
- A fluorescent or phosphorescent material, such as zinc sulfide, is coated on the tube behind the anode to detect cathode rays.
Appearance of Dark Space
- A dark space near the cathode appears when the pressure in the cathode ray tube is lowered substantially, indicating the absence of visible light.
High Voltage Effects
- When a very high voltage (approximately 10,000 volts) is applied between the two electrodes at normal pressure, cathode rays are emitted, demonstrating their properties.
Observations with Fluorescent Materials
- Fluorescent or phosphorescent materials allow the visualization of cathode rays, glowing when they strike the material, showing the rays' path.
Behavior in Electric/Magnetic Fields
- Cathode rays are deflected by electric or magnetic fields, indicating that they possess charge and are influenced by external forces.
Composition of Cathode Rays
- Cathode rays consist of electrons, the subatomic particles responsible for carrying charge.
Properties of Electrons
- Electrons possess a negative charge and a small mass, enabling their identification and manipulation in experiments.
Charge-to-Mass Ratio
- The charge-to-mass ratio (e/me) of an electron is approximately -1.76 x 10^11 coulombs per kilogram, providing insights into its fundamental properties.
Millikan's Charge Determination
- R.A. Millikan determined the charge of the electron through the oil drop experiment, allowing for accurate measurement of charge and verifying its value as approximately -1.6 x 10^-19 coulombs.
Modification of Discharge Tube Experiment
- The discharge tube experiment was modified by W. W. Thomson (Lord Kelvin) through perforation of the cathode, enabling better observation of emitted rays.
E. Goldstein's Experiment
- According to E. Goldstein's experiment, when high voltage is applied between the two electrodes, additional rays known as anode rays or positive rays are emitted behind the perforated cathode.
Mechanical Work Capability
- Cathode rays possess kinetic energy, allowing them to perform mechanical work when interacting with obstacles, energizing surrounding materials.
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Description
Test your knowledge on the discovery of the electron by J J Thomson through the Cathode ray discharge tube experiment and its implications for understanding sub-atomic particles.
