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Question
The saturation current in a triode valve can be changed by changing _____________ .
Options
the grid voltage
the plate voltage
the separation between the grid and the cathode
the temperature of the cathode
Solution
the grid voltage
Since the triode value consists of a space charge region near the cathode, this space charge region is affected by the grid voltage. If the grid voltage is made negative, it repels the electrons coming from the cathode and reduces current. If this voltage is made positive, it helps the electrons move towards the anode. Hence, this voltage is more effective in changing the plate current. Since, the saturated current in the triode is the maximum value of plate current, the saturated current in the triode valve is effectively controlled by the grid voltage. More negative is the grid voltage, less is the value of saturated current.
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