Connection of Resistor


Connection of Resistor

In a circuit, there are two basic ways, by which resistor can connect together. These are
1.       Series Connection and
2.       Parallel Connection

Besides this , there are also two types of connection . These are
1.       Star Connecton and
2.       Delta Connection


Series Connection of Resistor

Resistor is a two terminal passive component that used to limit the flow of current in a circuit. Assume the name of legs of R1 resistor is A and B. And the name of legs of R2 resistor is C and D. Now if B leg of R1 resistor is connected to C leg of R2 resistor and A and D legs are free or connect to other resistor in the same fashion, then such types of connection is called Series Connection.

Resistor: Series Connection






When two resistor are connected in Series, Resistance are added. Such that, if we calculate the total resistance of the circuit above, total resistance will be RCD= R1 + R2.

For practical example , let us consider, the value of R1 is 10Ω and R2 is 20Ω. If R1 and R2 are connected in series , total resistance will be
 R = R1 + R2
R = (10 + 20 )Ω = 30Ω.

If more than two resistors are connected in series such as R1 , R2 , R3…Rn, Therefore , Total resistance will  be
R = R1 + R2 +R3+ …+ Rn.


Parallel Connection of Resistor

If the leg A of R1 resistor is connected to the leg C of R2 resistor and leg B of R1 resistor is connected to the leg D of R2 resistor as shown in figure, such type of Connection is called Parallel connection. For a parallel connection, total resistance is reduced. Total resistance for the following circuit will be

Resistor: Parallel Connection










R = (1/R1) + (1/R2)
   = R1*R2 / (R1 + R2).
For practical example, let us consider, the value of R1 is 10Ω and R2 is 20Ω. If R1 and R2 are connected in parallel , total resistance will be

R = (1/R1) + (1/R2)
  = (1/10) + (1/20)
   = 10*20 / (10 + 20).
  = 200/ 30
  = 6.66Ω.

If more than two resistors are connected in Parallel such as R1 , R2 , R3…Rn, Therefore , Total resistance will  be
R = 1/R1 + 1/R2 +1/R3+ …+ 1/Rn.

N.B: It will be easier to calculate two resistor connected in parallel at a time. This two resistor will form one resistor, which will connect in parallel to another resistor and again we calculate the parallel connection of two resistor.
It two resistor of the same value are connected in parallel, their value will be half. For example if R1 and R2 boht are 10Ω and connected in parallel, their equivalent resistance will be half i.e 5Ω. And it does not require to calculate.

Besides this two common or basic types of connection, there are also two special type of connection. That cannot be solved using the formula of series –parallel connection. We will discuss it in our next post….

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