# NEET Physics Semiconductor Electronics Questions Solved

BOARD

Draw a circuit diagram of a transistor amplifier in CE configuration.

Define the terms: (i) Input resistance and (ii) Current amplification

factor. How are these determined using typical input and output

characteristics?                                                               (3 marks)

(1 1/2 marks)

Input resistance

${\mathrm{R}}_{{\mathrm{i}}_{\mathrm{B}}}={\left(\frac{∆{\mathrm{V}}_{\mathrm{BE}}}{∆{\mathrm{I}}_{\mathrm{B}}}\right)}_{{\mathrm{V}}_{\mathrm{CE}}}$                                                                              (1/2 mark)

Current amplification factor

${\mathrm{\beta }}_{\mathrm{ac}}={\left(\frac{∆{\mathrm{V}}_{\mathrm{C}}}{∆{\mathrm{I}}_{\mathrm{B}}}\right)}_{{\mathrm{V}}_{\mathrm{CE}}}$                                                    (1/2 mark)

The value of input resistance is determined from the

slope of IB verses VBE plot at constant VCE .

The value of current amplification factor is obtained from the slope

of collector IC verses VCE plot using different values of IB .       (1/2 mark)

(If a student uses typical charateristics to determine these

values, full credit of one mark should be given)

Difficulty Level:

Crack NEET with Online Course - Free Trial (Offer Valid Till September 24, 2019)