Resistors – Series circuit and Parallel Circuit

Resistors – Series circuit and Parallel Circuit

        Hello friends in our last topics we  have seen Resistance, Resistivity and Conductance, Conductivity and Temperature effect on Resistance .

           In this chapter we will learn about Resistors – Series circuit and Parallel Circuit

Resistors in Series or Series Circuit :

           Resistors R1, R2 and R3 are connected in Series combinations in which one end of resistor is connected to another end of resistor and forms a series. Therefore series circuit also can be called as end to end or cascade connection .

Conditions to be meet or satisfied for Series connection:

1.   There should be end to end connection between resistors in the circuit.

2.    Current should be same for all the element connected in Series .

Resistance of Series Combinations

The equivalent resistance of series combination of resistors is the sum of all resistors connected in series .

RT   = R1+R2+R3

For n numbers of resistors RT  is given by

RT   = R1+R2+………..Rn

Sample problem: 

Using the circuit diagram -Find the value of missing resistance R. 

Answer:

From Ohm's law we know that

Resistance = Voltage/current,

therefore

Resistance=50V/2A
Resistance=25 Ω

Resistors in series:

Resistance=8+5+2+4+R
Resistance=19+R

Lets see ,

25=19+R

R=25-19 Ω

R= 6 Ω

Resistors in Parallel or Parallel Circuit :

             Resistors R1, R2 and R3 are connected in Parallel  combinations in which Resistors are connected in across with each other . One end of resistor is connected to junction point of another resistor . 

Conditions to be meet or satisfied for Series connection:

1.   There should be resistors connections across to each other 

2.   Voltage should be same for all the element connected in Parallel  .

Resistance of Parallel Combinations

The equivalent resistance of parallel combination of resistors

Note : The equivalent resistance always smaller than the smallest resistance in parallel resistors circuit .

Example problem: 

Calculate the equivalent resistance "R" across the voltage V in the circuit as  below ? 

Answer:

Since these resistors are in parallel we know from the equation above that
1/R = ¼ + 1/5 + 1/20
1/R = 5/20 + 4/20 + 1/20
1/R = 10/20 = ½
R = 2 Ω

As per our statement equivalent resistance will always be less than the smallest resistor in parallel. 

Also Learn about basic concepts ofelectrical engineering.