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What is series-parallel ?
What is series-parallel ?
This topics is about combinations of series and parallel circuit.
The understanding of the combination of circuit is crucial and are been applied in many control circuits.
Rules and Formula for series-parallel circuit
Rules and Formula for series-parallel circuit
Total resistance, Rt = R1 + ((R2 x R3) ÷ (R2 + R3))
Total resistance of R2 and R3 shall be following two resistors from previous topics.
While value of R1 is added according to series formula
Total current, It = IR1 = (IR2 + IR3)
Current flowing through R1 is the same as total current.
While the current at R2 and R3 is added up to be same as R1 and It.
Total voltage, Vt = VR1 + (VR2 = VR3) and VR2/VR3 = Vt - VR1
Voltage between R2 and R3 is the same. While R1 voltage is added together with R2 and R3.
Example calculation
Example calculation
1) Given R1 is 40 Ω , R2 is 60 Ω and R3 is 80 Ω .
a) find total resistance, Rt ?
Solution: Rt = R1 + (( R2 x R3 )÷( R2+ R3 ))
Rt = 40Ω + ((60Ω x 80Ω) ÷ (60Ω + 80Ω)) = 74.28 Ω
b) find total current (It) if given voltage is 120 volts.
Solution: It = Vt ÷ Rt
It = 120 v ÷ 74.28 Ω = 1.615 A
c) Calculate the voltage at resistor R1.
Solution: VR1 = IR1 x R1
VR1 = 1.615 A x 40 Ω = 64.6 volt
d) Calculate the voltage at resistor R2 and R3.
Solution: VR2, VR3 = Vt - VR1
VR2/VR3 = 120v - 64.6v = 55.4 volt
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