Difference Between Resistors in Parallel and Series

Difference Between Resistors in Parallel and Series

Connecting Resistors in Parallel and Series

Different types of conditions are observed while connecting resistors in
parallel and series. The connection type of resistors affect the current, voltage and total resistance value. Let’s discuss the characteristics of connecting resistors in parallel and series

What are Resistors in Parallel Combination?

 

When both of the terminals of the resistors are connected to each other
in a circuit the arrangement is called resistor in parallel.

Flow of Current in Parallel Combination

There is a difference in the flow of current when connecting resistors in parallel and series. Following points show the flow of current in parallel networks of resistors.

  • When current passes through resistors in parallel it can pass from more
    than one path because parallel arrangement provides more than one paths. Due to this reason parallel circuits are also called current dividers.
  • The current is proportional to the value of the resistance, And not balanced equally in all the branches in parallel circuits.
  • The voltage drop remains same in the parallel circuits of resistors as well as for all other elements connected in parallel combination.
  • The circuits in which resistors are connected in parallel combination are called parallel resistive circuits. They provide more than one path to the current coming from same voltage source.
  • Calculating the current using Ohm’s law I = V / R

How do you calculate resistors in parallel?

In case of parallel resistors the reciprocal value of each resistor is
added instead of the normal resistance to find the equivalent resistance.

      Resistors in Parallel Formula

The following equation 1/RT = (1/R1 ) + (1/R ) + (1/R3)…….+1/Rn is used to find the equivalent resistance RT of (n) number of resistors connected in parallel combination in an electrical circuit.

In parallel arrangement if two resistors are equal, i.e having the same value, the equivalent resistance RT will become equal to R/2 i.e half of the resistance of one resistor,

In case of three equals resistors equivalent resistance RT will become R/3 and so on.

The main point to note is that the equivalent resistance is always less than the resistance of a smallest resistor in the circuit connected in parallel combination. Due to this the equivalent resistance Rt will decrease with the increase in the number of parallel resistors.

Resistors in Parallel Formula Examples

Example 1

Assume an electrical circuit having two parallel resistors R1 = 10 Ohm & R = 20 Ohm, The equivalent resistance of the circuit will be Rt = 1/ ((1/10) + (1/20)) = 6.7 Ohm.

Example 2

Assume R1 = 100 Ohm & R = 100 Ohm, The equivalent resistance of the circuit will be Rt = 1/((1/100) + (1/100)) = 50 Ohm.

What is the Current in Parallel Resistors?

We can say that the total current passing through a parallel resistive circuit will be the sum of all the currents passing through each parallel network.

The voltage remains same throughout all the branches but the amount of currents passing through each parallel branch is not always equal because it depends upon the resistive value of each branch.

If the resistors of all branches are same then the amount of current will also be the same but if the resistors are not identical in resistivity, the amount of current also changes.

What Are Resistors in Series?

When the resistors are connected in such a way that one end of a resistor is
connected to the end of an other resistor and so on in the form of a chain, this type of combination is called resistor in series.

In this combination when the current follows from one resistor it has no path to go except passing from the next resistor.

What Is The Current In Series Circuit?

All the resistors in series of one network have a common current passing through them because there is no other path for the flow of current.

Due to this reason the total amount of current passing through all the resistors is also the same.

For example, Let’s say R1, R2, R3 and R4 are the resistors connected in series with current IR1, IR2 ,IR3  & IR4 respectively passing through them.

If 5A of current is passing through the resistor R1 then IR1 = IR2 = IR3 = IR4 = 5A

How to Calculate Resistors in Series?

As the current passes through each resistor is same in amount due to series combination the equivalent resistance will be the sum of the resistances of all the resistors connected together in series.

For example, Let us consider the four resistors connected in series with resistances R1, R2, R3 and R4 respectively. Now the equivalent resistance RT will be RT = R1 + R2 + R3 + R4

The equivalent resistance may be defined as the value of resistance which can be used for all the resistors in series if a circuit without changing the value of
current and voltage.

Resistors in Series Formula Examples

Example 1

Assume an electrical circuit having two parallel resistors R1 = 10 Ohm & R = 20 Ohm, The equivalent resistance of the circuit will be Rt = 10 + 20 = 30 Ohm.

Example 2

Assume R1 = 100 Ohm & R = 100 Ohm, The equivalent resistance of the circuit will be Rt = 100 + 100 = 200 Ohm.

Voltage in Series Resistors

Voltage shows a different behavior when connecting resistors in parallel and series.

The voltage in series combination does not remain constant like current. Its because the individual resistance of each resistor changes the voltage when current passes through it into the next resistor of the series.

The voltage is distributed in all resistors differently according to some rules.

  • As the voltage is divided in all the resistors, that’s why the series networks are also called as voltage dividers.
  • The number of resistors connected in the series determines the number of voltages divided in the resistors which means N number of resistors in a series contain N number of voltages divided among them.

In order to find the voltages of resistors in any series combination of a circuit, Ohm’s Law is used which is V=I×R. This law can also be used in finding the current or resistance of the resistors throughout the series connected circuit.

Read Our Other Article : What is Ohm’s Low?