Q15 of 49 Page 352

The dynamic plate resistance of a triode valve is 10 kΩ. Find the change in the plate current if the plate voltage is changed from 200 V to 220 V.

Given rp=10 KΩ = 104Ω, VP1=200V, VP2=220 V

The dynamic resistance of triode is defined as,



where ΔVp is the change in plate voltage and Vg is the grid voltage and ΔIp is the change in plate current



More from this chapter

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13

A triode valve 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.

 14

Calculate the amplification factor of a triode valve which has plate resistance of 2 kΩ and transconductance of 2 millimho.

 16

Find the values of rp, μ and gm of a triode operating at plate voltage 200 V and grid voltage –6 V. The plate characteristics are shown in figure.


 17

The plate resistance of a triode is 8 kΩ and the transconductance is 2.5 millimho.

(a) If the plate voltage in increased by 48 V, and the grid voltage is kept constant, what will be the increase in the plate current?


(b) With plate voltage kept constant at this increased value, how much should the grid voltage be decreased in order to bring the plate current back to its initial value?