Voltage in Series and Parallel Circuits
Voltage behaves differently depending on whether electrical components are connected in series or in parallel. Understanding these differences is essential for designing, analysing and troubleshooting electronic circuits.
Series Circuits
In a series circuit, components are connected one after another, forming only one path for current to flow.
Because the current is the same through every component, the supply voltage is shared between them.
Voltage Division
Each resistor receives a portion of the total supply voltage. The larger the resistance, the larger the voltage drop across it.
For example, if a 12 V battery is connected to two equal resistors in series:
- Supply Voltage = 12 V
- Rโ = 1 kฮฉ
- Rโ = 1 kฮฉ
Each resistor has a voltage drop of:
12 V รท 2 = 6 V
The sum of all voltage drops equals the supply voltage.
Voltage Divider Circuits
A voltage divider is one of the most common applications of series resistors.
It allows a smaller voltage to be obtained from a larger supply voltage.
Examples include:
- Sensor circuits
- Microcontroller inputs
- Biasing transistors
- Reference voltages
Parallel Circuits
In a parallel circuit, every component is connected directly across the same two supply terminals.
Because each branch is connected across the source, every branch receives the full supply voltage.
Voltage in Parallel Branches
Consider a 12 V battery connected to three resistors in parallel.
| Branch | Voltage |
|---|---|
| Rโ | 12 V |
| Rโ | 12 V |
| Rโ | 12 V |
Although the current in each branch may be different, the voltage across every branch is exactly the same.
Series vs Parallel Voltage
| Series Circuit | Parallel Circuit |
|---|---|
| Voltage is divided. | Voltage is the same across every branch. |
| Current is the same. | Current is divided. |
| One current path. | Multiple current paths. |
Practical Examples
| Application | Circuit Type |
|---|---|
| Voltage Divider | Series |
| LED String | Series |
| House Wiring | Parallel |
| Power Distribution | Parallel |
| Automotive Accessories | Parallel |
| Battery Cells | Series or Parallel |
Kirchhoff's Voltage Law
Kirchhoff's Voltage Law states that the total voltage around any closed electrical loop is zero.
This means that the sum of all voltage drops in a series circuit equals the supply voltage.
Common Mistakes
- Assuming voltage is always divided.
- Confusing voltage with current.
- Thinking larger resistors receive less voltage in series circuits.
- Believing parallel components share voltage.
Remember:
- Series โ Voltage divides.
- Parallel โ Voltage stays the same.
Key Points
- Voltage divides across series components.
- The total voltage drops equal the supply voltage.
- All branches of a parallel circuit receive the same voltage.
- Series circuits have one current path.
- Parallel circuits have multiple current paths.
- Understanding voltage distribution is essential for circuit design.