Electrical Resistance in Serial and Parallel Networks
Resistors in parallel and serial connections.
Serial Connection
The total resistance for resistors connected in series can be calculated as
R = R1 + R2 + .... + Rn (1)
where
R = resistance (ohm, Ω)
Example - Resistors in Series
Three resistors 33 ohm, 33 ohm and 47 ohm are connected in serial. The total resistance can be calculated as
R = (33 ohm) + (33 ohm) + (47 ohm)
= 113 ohm
Parallel Connection
The total resistance for resistors connected in parallel can be calculated as
1 / R = 1 / R1 + 1 / R2 + .... + 1 / Rn (2)
Equivalent resistance of 2 resistors connected in parallel can be expressed as
R = R1 R2 / (R1 + R2) (3)
Example - Resistors in Parallel
Three resistors 33 ohm, 33 ohm and 47 ohm are connected in parallel. The total resistance can be calculated as
1 / R = 1 / (33 ohm) + 1 / (33 ohm) + 1 / (47 ohm)
= 0.082 (1 / ohm)
R = 1 / (0.082 ohm)
= 12.2 ohm
If the battery voltage is 12 V - the current through the circuit can be calculated by using Ohm's law
I = U / R
= (12 V) / (12.2 ohm)
= 0.98 ampere
The current through each resistor can be calculated
I1 = U / R1 = (12 V) / (33 ohm) = 0.36 ampere
I2 = U / R2 = (12 V) / (33 ohm) = 0.36 ampere
I3 = U / R3 = (12 V) / (47 ohm) = 0.26 ampere
Resistors Connected in Parallel - Calculator
Add the resistances for up to five parallel connected resistors and (optionally) the circuit voltage.
The total resistance and current - and the individual currents in all resistors - will be calculated:
R1 (ohms)
R2 (ohms)
R3 (ohms)
R4 (ohms)
R5 (ohms)
Voltage (V)
I1 (amps)
I2 (amps)
I3 (amps)
I4 (amps)
I5 (amps)
R (ohms)
I (amps)
