Question

In a cathode ray tube, the filament is made up of tungsten because

• A. It can generate large number of electrons as it has small work function
• B. It can generate large number of electrons as it has low melting point
• C. It can generate large amount of heat, to heat the cathode, as it has low resistivity and high melting point
• D. It can generate large amount of heat, to heat the cathode, as it has high resistivity and high melting point

Answer 1

The correct option is D

It can generate large amount of heat, to heat the cathode, as it has high resistivity and high melting point

Tungsten is the most suitable to be used as a filament because It can generate large amount of heat , to heat the cathode, as it has high resistivity and high melting point of 3655 K.