Question

State the approximate voltage V${}_1$ used to heat the filament in a cathode ray tube.

• A. 6 V
  
• B. 1 V
  
• C. 1000 V
• D. 6000 V
  

Answer 1

The correct option is A 6 V

The tungsten filament heater, operated from a low voltage supply $\left(about6Vac\right)$ is surrounded by the metal cathode.