question_answer

Plate current will be maximum when:

A)  both the grid and anode are negative

B)  both the grid and anode are positive

C)  grid is positive and anode is negative

D)  grid is negative and anode is positive   

Correct Answer: B

Solution :

Key Idea: Grid controls the current in the plate circuit.    Triode valve consists of a cathode, grid and anode. When current is passed in the filament by connecting it to a battery, the filament is heated and it heats up the cathode, so electrons start emitting from the cathode. Anode plate is connected to the positive terminal of a   battery. Thus, anode is positive with respect to cathode, electrons being negatively charged get attracted towards anode and a continuous plate current flows. When both grid and anode are positive maximum plate current flows.