Tutorial 4 Question 4
Find the power in the 2W resistor R6 using Thevenin's theorem.
Remove R6 from the circuit
Redraw the circuit after finding the resistance, RA of the parallel branch R3||R4.
Redraw the circuit and calculate the voltage across the break AB which is the voltage across RA = VT. Remember that 20V is dropped across R1 and also across R2+RA. Since R2 = RA = 5W half of the voltage is dropped across each resistor VT = 10V
Remove V1 and replace it with a short circuit
This action also short circuits R1 out of the circuit
Determine Resistance looking into the break AB = RT
RT = (RAxR2) / (RA+R2) + R5 + R7 = 14.5W
Determine the value of the current from the Thevenin equivalent circuit
I = VT/(RT + R6) = 10/16.5 = 0.606A
Power dissipated by R6 = I x I x R = 0.73 Watts