Physics Electron, Photon, Photoelectric Effect and X-rays Cathode Rays and Positive Rays Single Correct MCQ
Published on: September 12, 2026

An oxide coated filament is useful in vacuum tubes because essentially

A
It has high melting point
B
It can withstand high temperatures
C
It has good machanical strength
D
It can emit electrons at relatively lower temperatures

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Text Solution

Verified by Experts
The correct answer is:
D
Step 1: Understand the function of the oxide coating on the filament in vacuum tubes.
Step 2: The oxide coating reduces the work function of the filament, making it easier for electrons to be emitted when heated.
Step 3: This allows the filament to emit electrons at lower temperatures compared to uncoated filaments.
Therefore, Option D is the correct answer.

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