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Question
A triode value operates at Vp = 225 V and Vg = −0.5 V.
The plate current remains unchanged if the plate voltage is increased to 250 V and the grid voltage is decreased to −2.5 V. Calculate the amplification factor.
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Solution
Amplification factor for a triode valve,
\[\mu = \frac{\text{Change in Plate Voltage}}{\text{Change in Grid Voltage}}\]
At constant plate current,
\[\mu = \left(\frac{\delta V_P}{\delta V_G}\right)_{i_P = constant} \]
\[\mu = \frac{250 - 225}{2 . 5 - 0 . 5}\]
\[\mu = \frac{25}{2} = 12 . 5\]
This implies that the amplification factor of the triode is 12.5
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