parallel circuit

Previous lecture I was discussing about series circuit. This lecture will discuss about parallel circuit.

What is parallel circuit?

When one end of each resistance or any other element Is joined to a common point and the other end of each resistance or any other element is joined to another common point so that there are as many paths for current flow as the number of resistance or any other element, is called a parallel circuit.

parallel circuit

Consider three resistances R1, R2 and R3 are connected in parallel across a battery of V volt as show the figure at the right side. The total current I divided into three parts that means I1 flowing through R1, I2 flowing through R2 and I3 flowing through R3.obviously, the voltage across each resistance is the same and there are as many current paths as the number of resistance .by ohms law 

 I1=V/R1; I2=V/R2; I3=V/R3

Now, I=I1+I2+I3

          =V/R1+V/R2+V/R3

          =V (1/R1+1/R2+1/R3)

     I/V=1/R1+1/R2+1/R3

But I/V is the total resistance RT of the parallel resistance as the figure at the right side.

equivalent parallel circuit

For that, 1/RT=1/R1+1/R2+1/R3

When a number of resistances are connected in parallel, the mutual of total resistance is equal to the sum of mutual of individual resistance.

Important notes for parallel circuit

1. The voltage across each resistance of a parallel circuit is the same.

2. The total resistance of a parallel circuit always less than the smallest of the resistance.

3. If n resistor, each of R ohms, is connected in parallel, then the total resistance is

 RT=R/n

Advantage of parallel circuit:

1. If a break occurs in any one of the branch circuit, it will have no effect on other branch circuit.

2.it can we easily use as a lighting circuit.