For each circuit in the following figure let 100 Find the

For each circuit in the following figure, let ? = 100. Find the operating point.

Operating point means zero signal values of IC and VCE, that when a DC condition is prevailed in a transistor circuit.

voltage across R2 resistance is, VccxR2/(R1+R2)= 24x42/100=10.08V

Here R1 and R2 are assumed in series as IB base current is negligible. So it is assumed that cuurent flowing through R1 is same as through the R2.

Now R2 arm voltage will be same as ,

VR2=VBE+IERE

for silicon transistor VBE=0.7V

again IE=IC if IB is less

so,

10.08=0.7+ICxRE

ICXRE=10.08-0.7

IC=0.938mA as RE is in Kohm

Now applying KVL in outer loop we get,

VCC=VCE+IERE

or, VCC=VCE+ICRE

VCE=VCC-ICRE= 24-0.938*10=14.62V

so, VCE=14.62V and IC=0.938mA this is the Q point or operating point and written as (14.62V, 0.938mA).