System of resistors:
Let’s study some basic examples to study the combination of resistors.
Resistors in series:
The equivalent resistance of combination of resistance connected in series is given by,
1) Equivalent resistance , Rs = R1 + R2 + R3
Resistors in parallel:
The equivalent resistance of combination of resistance connected in parallel is given by,
Ex. 1) Find the equivalent resistance in following circuit if value of each resistance is 10 Ω
Solution: Data, R1=10 Ω, R2=10 Ω, R3=10 Ω, R4=10 Ω
As we can see in the figure above, resistors R2 & R4 are connected in parallel, so their equivalent resistance can be obtain as
Hence the equivalent resistance of circuit is .25Ω
Ex. Find the value of current in following circuit.
Let R1=10 Ω, R2=20 Ω, R3=20 Ω, R4=20 Ω, R5=25 Ω
V= 220 V
To find total current ‘I’, first we need to find total resistance of circuit.
As we can see in diagram, R2, R3 and R4 are connected in parallel, then equivalent resistance of this part circuit is say RP
I = V/R
∴ I = 220/41.67
∴I = 5.28 A
Hence 5.28 A current will be flow through the given circuit.