Question

Which of the following conditions is most suitable to be maintained in the discharge tube?

• A. High voltage, high pressure
• B. High voltage, low pressure
• C. Low voltage, low pressure
• D. Low voltage, high pressure

Answer 1

The correct option is B

High voltage, low pressure

Explanation for correct option: (B)

High voltage, low-pressure conditions are most suitable to be maintained in the discharge tube as:

1. Low pressure indicates that there are fewer gas molecules in the discharge tube. When the number of molecules is low, collisions between electrons moving fast towards the anode and gas molecules occur, resulting in the creation of cathode rays.
2. The low pressure in the tube is required so that the electron beam's passage is not significantly hampered by collisions with air molecules.
3. Furthermore, high voltage raises the kinetic energy of electrons, which enhances the likelihood of electron removal from gaseous molecules.
4. To give the electrons enough kinetic energy to make the fluorescent screen glow when they hit it, you'll need a very strong accelerating voltage.

Hence, option (b) is correct.