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Difficulty: MediumConduction of Electricity Through Gases and Cathode Rays

In a gas discharge tube operated at a very low pressure of approximately 0.01 mmHg0.01\text{ mmHg}, cathode rays are produced. Which of the following statements accurately describes a characteristic property of cathode rays?

  1. A
    They are electromagnetic waves of extremely high frequency.
  2. They cast sharp shadows of opaque objects placed in their path.Answer
  3. C
    They are deflected toward the negatively charged plate in an electric field.
  4. D
    They originate from the anode and travel toward the cathode.

Answer

Cathode rays cast sharp shadows of opaque objects placed in their path because they travel in straight lines.
The correct option correctly states that cathode rays cast sharp shadows of opaque objects in their path. This phenomenon demonstrates that cathode rays travel in straight lines from the cathode.

Step-by-Step Solution

1
Identify the nature of cathode rays
Cathode rays are streams of electrons emitted from the cathode in a low-pressure discharge tube.
The high electric potential difference accelerates free electrons away from the cathode surface.
2
Analyze propagation behavior
Cathode rays travel normal to the cathode in straight lines.
Because they travel in straight lines, any opaque barrier (such as a metal cross) blocks the stream completely, casting a clear shadow on the fluorescent tube wall.

Key Concept

Properties of Cathode Rays
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Topics

Conduction of Electricity Through Gases and Cathode Rays

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