A parallel circuit is formed when two or more components are connected to the same voltage source. A common application of parallel circuits is typical house wiring to the power line, with many lights and appliances connected across the 120V source.
A basic parallel circuit with 2 resistors looks like this. In practical sense, the circuit can be imagined something like this(right fig)
How to find the Equivalent Resistance?
Equivalent resistance REqcan be calculated in two ways. First, find the individual branch currents using Ohm's law. Then find the total current IT by adding the individual branch currents.
IT = I1 + I2 + I3 + I4......
Then REq= VA / IT
When a circuit consists of two resistors, the equivalent Resistance can be calculated as below.
In the fig above lets assume R1=40Ω, R2=60Ω
REq= R1 X R2 / R1 + R2
REq= 40 X 60 / 100 = 2400/100 = 24Ω
When a circuit consists of three resistors, and all three resistors are equal, then the equivalent Resistance can be calculated as below.
R1 = R2 = R3 = 60kΩ, then the equivalent Resistance can be calculated as below.
REq= Value of one Resistance / Number of Resistances = 60kΩ / 3 = 20kΩ
When a circuit consists of many resistors, and all are of unequal values, then the equivalent Resistance can be calculated as below.
1 / REq= 1 / R1 + 1/ R2 + 1/R3 + 1/ R4.........etc
REq= 1 / (1 / R1 + 1/ R2 + 1/R3 + 1/ R4.........etc)
A basic parallel circuit with 2 resistors looks like this. In practical sense, the circuit can be imagined something like this(right fig)
How to find the Equivalent Resistance?
Equivalent resistance REqcan be calculated in two ways. First, find the individual branch currents using Ohm's law. Then find the total current IT by adding the individual branch currents.
IT = I1 + I2 + I3 + I4......
Then REq= VA / IT
When a circuit consists of two resistors, the equivalent Resistance can be calculated as below.
In the fig above lets assume R1=40Ω, R2=60Ω
REq= R1 X R2 / R1 + R2
REq= 40 X 60 / 100 = 2400/100 = 24Ω
When a circuit consists of three resistors, and all three resistors are equal, then the equivalent Resistance can be calculated as below.
R1 = R2 = R3 = 60kΩ, then the equivalent Resistance can be calculated as below.
REq= Value of one Resistance / Number of Resistances = 60kΩ / 3 = 20kΩ
When a circuit consists of many resistors, and all are of unequal values, then the equivalent Resistance can be calculated as below.
1 / REq= 1 / R1 + 1/ R2 + 1/R3 + 1/ R4.........etc
REq= 1 / (1 / R1 + 1/ R2 + 1/R3 + 1/ R4.........etc)
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