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Difficulty: MediumConduction of Electricity Through Gases and Cathode Rays

Match each discharge tube phenomenon or experimental setup in Column A with its correct physical description or property in Column B.

  • Faraday dark spaceA non-luminous region separating the negative glow from the glowing gas column at moderate low pressure (≈1 mmHg\approx 1\text{ mmHg})
  • Crookes dark spaceA dark region surrounding the cathode that expands to fill almost the entire tube at very low pressure (≈0.01 mmHg\approx 0.01\text{ mmHg})
  • Positive columnA bright, luminous stream of ionized gas extending toward the anode
  • Paddle wheel in a discharge tubeDemonstrates that cathode rays carry kinetic energy and possess mechanical momentum

Answer

Faraday dark space matches the non-luminous region separating the negative glow from the positive column (≈1 mmHg\approx 1\text{ mmHg}); Crookes dark space matches the dark region around the cathode that expands at very low pressure (≈0.01 mmHg\approx 0.01\text{ mmHg}); Positive column matches the bright luminous stream extending toward the anode; Paddle wheel matches the demonstration of kinetic energy and mechanical momentum of cathode rays.
Each feature of discharge tubes corresponds to specific gas pressure stages and physical properties of cathode rays. Faraday dark space is the non-luminous region at moderate pressures; Crookes dark space expands near the cathode at very low pressure (≈0.01 mmHg\approx 0.01\text{ mmHg}); the positive column is the luminous glowing gas stream; and the paddle wheel experiment proves cathode rays possess mechanical momentum.

Step-by-Step Solution

1
Analyze discharge tube pressure stages.
At moderate pressures (≈1 mmHg\approx 1\text{ mmHg}), the Faraday dark space appears between the negative glow and the luminous positive column.
Ionization processes create distinct bright and dark regions based on electron acceleration distances between collisions.
2
Identify high-vacuum phenomena.
At very low pressures (≈0.01 mmHg\approx 0.01\text{ mmHg}), the Crookes dark space expands across almost the entire length of the discharge tube.
Fewer gas molecules allow electrons to travel longer distances without colliding, shifting ionization further down the tube.
3
Correlate mechanical experiments with cathode ray properties.
A paddle wheel mounted on glass rails rotates when hit by cathode rays, showing they possess momentum.
Electrons have mass mm and velocity vv, transferring kinetic energy and momentum (p=mvp = mv) upon impact.

Key Concept

Conduction of Electricity Through Gases and Cathode Rays
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Topics

Conduction of Electricity Through Gases and Cathode Rays

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