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Draw the diagram of the circuit arangement used for studying the 'input' and the 'output' characteristics of an n-p-n transistor inits CE configuration. Briefly explain how these two types of characteristics are obtained and draw these characteristics. (b) 'Define' the terms (i) Input resistance, (ii) Output resistance , (iii) Current amplification factor, for a given transistor. |
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Answer» Solution :(a) N/A (i) The input resistance `r_i` of the TRANSISTOR in CE configuration is defined as the ratio of the small CHANGE in base -EMITTER voltage to the corresponding small change in the base current, when the collector-emitter voltage is kept fixed. Thus. `r_i[(DeltaV_BE)/(DeltaI_B)]_(V_(CE)="constant")`. (ii) The output resistance `r_0` of a transistor in CE configuaration is definded as the ratio of the small change in the collector-emitter voltage to the corresponding change in the collector current when the base current is kept constant. Thus, `r_0[(DeltaV_CE)/(DeltaI_C)]_(I_(B)="constant ")`. (ii) Current amplification factor `(beta)` : It is defined as the ratio of the change in collector current to the small change in base current at constant collector-emitter voltage `(V_CE)` when the transistor is in the acitve state. `beta_ac=[(DeltaI_C)/(DeltaI_B)]_(V_(CE)="constant")` |
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