# Series and Parallel Circuits – Top 5 Differences, Circuit Diagram and Explanation

In Electrical Engineering, two-terminal components can be connected in series or parallel configurations.  Electrical components connected in series are along a single “electrical path”. Each component in the series network has the same flow of electric current through it. The flow of current through any component is equal to the current through the network. The voltage across the series network equals the sum of the voltages across each component. On the other Electrical components connected in parallel are connected along multiple paths. The current through network equals the sum of current through all components. Current divides in a parallel network, however, parallel components have the same voltage across them, and the voltage across any component is equal to the voltage across the network.

## Series Circuits

A series circuit involves the head-to-head connection between two components. In such circuits, components are connected in end-to-end lines. The figure below illustrates three resistors R1, R2, and R3 connected in a series configuration.

The figure below depicts a practical series circuit where three resistors R1, R2, and R3 are connected in series to a voltage source Vs.

The +ve terminal of source voltage (Vs) is connected to one end of resistor R1, another end of R1 connects to R2, which in turn connects to R3 and finally, the other end of R3 connects to the negative terminal of the source, thereby completing the circuit.

### Current in Series Circuits

The current always remains the same through all series components.

The voltage source Vs will produce a current Is. The current Is goes through every component in the circuit. All three resistors R1, R2, and R3 will carry the same current Is.

If I1, I2, and I3 are currents through R1, R2, and R3.

Then, I1 = I2 = I3 = Is

The numerical value of the current in the above series circuit can be found by using Ohm’s law Is = Vs/Rs.

Is = Vs/(R1 +R2 + R3)

### Voltage in Series Circuits

Voltage always divides in series circuits.

In case of series circuits, the voltage Vs is the sum of the voltage drops of the individual components (resistance units).

If V1, V2, and V3 are voltage drops across R1, R2, and R3, then

Vs  = V1 + V2 + V3

### Resistance in Series Circuits

The total resistance of two or more components is equal to the sum of individual resistances. If Req is the equivalent resistance of a series circuit and R1, R2, and R3 are individual resistors, then

Req  = R1 + R2 + R3

## Parallel Circuits

A parallel circuit configuration involves two or more components connected in such a way that one end of all components shares a common electrical node and the other end shares another common electrical node. The figure below illustrates three resistors R1, R2, and R3 that are connected in parallel configuration.

The figure below depicts a practical parallel circuit where three resistors R1, R2, and R3 are connected to source voltage Vs.

### Voltage in Parallel Circuits

In the case of parallel circuits voltage remains the same across all components.

If V1, V2, and V3 are voltage drops across R1, R2, and R3, in above circuit then

Vs  = V1 = V2 = V3

### Current in Parallel Circuits

Current divides in case of parallel circuits.

The total current in a parallel circuit is the sum of the currents through the individual components. If Is is the source current supplied to the circuit, and I1, I2, I3 are values of current flowing through resistors R1, R2, and R3, then

Is  = I1 + I2 + I3

### Resistance in Parallel Circuits

The equivalent resistance of parallel resistors can be found by taking the reciprocals of each resistor and then by taking the reciprocal of the sum.

The general formula for n number of resistors connected in parallel configuration is:

In case of three resistors connected in parallel:

## Difference between Series and Parallel Circuits

The chart below illustrates the difference between series and parallel circuits:

## Practical applications of Series and Parallel Circuits

• Practical Applications of Series Circuits involve battery banks.
• Practical applications of parallel circuits involve wiring in our homes.

## FAQs about Series and Parallel Circuits

Given below are few important questions related to series and parallel circuits that can be asked in electrical interviews and job tests.

### What are top 5 Differences between Series and Parallel Circuits

A series circuit comprises of the head to head connection between two components. Current always remains in such circuits while the voltage divides among series components. A parallel circuit configuration involves two or more components in which one end of all components share a common node and other end shares another common node.

• Connections: Series components share one single node and there is no other connection. In simple terms, the head of one component connects to the tail of other one and there is no other connection in between them. On the other hand heads of all parallel components share one common node, and tail shares other common nodes.
• Voltage: The input voltage is divided into series components. The voltage across parallel components always equals the applied input voltage.
• Current: Current always remains same in series components. Current is shared between the parallel connected devices.
• Limitations: A damaged component in series circuit opens the overall circuit thus abolishing the current flow through the circuit. In a parallel circuit, a damaged component opens the branch, other parts of circuit remain intact.
• Resistance: Series resistors are simply added to obtain the equivalent resistance. Parallel resistors require a specific formula for appropriate solution.

### What happens to the resistance in a series circuit?

In a series circuit, the total resistance is equal to the sum of individual resistances. The resistance increases as more resistors are added in series.

### What happens to the resistance in a parallel circuit?

In a parallel circuit, the reciprocal of the total resistance is equal to the sum of the reciprocals of individual resistances. The resistance decreases as more resistors are added in parallel.

### How does voltage behave in series and parallel circuits?

In a series circuit, the total voltage across all components is equal to the sum of the individual voltage drops across each component. In a parallel circuit, the voltage across each component remains the same.

### How does current behave in series and parallel circuits?

In a series circuit, the same current flows through all components. In a parallel circuit, the total current divides among the branches, with the current in each branch determined by the resistance of that branch.

### Can I mix series and parallel components in a circuit?

Yes, it is possible to have a combination of series and parallel components in a circuit. Complex circuits often involve a mix of series and parallel connections to achieve desired functionalities.

### What are the advantages of using a series circuit?

In a series circuit, all components receive the same current, making it suitable for applications where a uniform current flow is required. Additionally, the total resistance is the sum of individual resistances, which can be useful in certain calculations.

### What are the advantages of using a parallel circuit?

Parallel circuits offer several advantages, such as the ability to power multiple components independently, each with the same voltage. It also provides redundancy, as the failure of one component does not affect the operation of others.