- Series Circuit Definition: A series circuit is defined as a connection where components are linked in a single path for current flow.
- Voltage Drop: Voltage drops in a series circuit occur as electrical energy is converted into other forms when current passes through resistors.
- Ohm’s Law: Ohm’s law helps calculate voltage drops in series circuits, showing that the total drop equals the source voltage.
- How to Add Voltage in Series: To add voltage in series, sum the voltages of all sources, considering their polarity.
- Applications: Series circuits are used in voltage dividers, fire alarms, toys, and decorative lighting.
What are Voltages in Series?
A series circuit is defined as a connection where two or more electrical components are linked in a chain. In this circuit, there is only one path for the charge to flow. Voltage, or potential difference, is the variation in charge between two points in a circuit. This article discusses voltage in series circuits in detail.
The battery in a circuit provides energy, allowing charge to flow and creating a potential difference between the circuit ends. For example, a 2-volt cell will create a 2-volt potential difference across the external circuit.
The electric potential at the positive terminal is 2 volts higher than at the negative terminal. When charge flows from positive to negative, it loses 2 volts of electrical potential.
This is termed as voltage drop. This happens when the electrical energy of the charge is converted into some other forms (mechanical, heat, light etc) while passing through the components (resistors or load) in the circuit.
If we consider a circuit with more than one resistor connected in series and are powered with a 2V cell, the total loss of electrical potential is 2V. That is, there will be a certain voltage drop in each connected resistor. But we can see that the sum of the voltage drop of all the components will be 2V which is equivalent to the voltage rating of the power source.
In a series circuit with multiple resistors powered by a 2V cell, the total voltage drop across all resistors is 2V. Each resistor will have a voltage drop, and the sum of these drops equals the power source’s voltage.
Mathematically, we can express it as
By using Ohm’s law the individual voltage drops can be calculated as
Now, we can assume a series circuit comprises of 3 resistors and powered by a 9V energy source. Here, we are going to find out the potential difference at a different location during the passage of current throughout the series circuit.
The locations are marked in red color in the circuit below. We know that current passes in the direction from the positive terminal towards the negative terminal of the source. The negative sign of the voltage or potential difference represents the loss in potential due to the resistor.
The electrical potential difference of different points in the circuit can be represented with the help of a diagram called the electric potential diagram that is shown below.
In this example, the electrical potential at A = 9V since it is the higher potential terminal. The electrical potential at H = 0V since it is the negative terminal. When the current passes through the 9V power source, the charge gains 9V of electrical potential, which is from H to A. While the current passes throughout the external circuit, the charge loses this 9V completely.
Here, this happens in three steps. There will be drop-in voltage when the current passes through the resistors but no voltage drop occurs when the passage is through the mere wire. So, we can see that between the points AB, CD, EF and GH; there is no voltage drop. But between points B and C, the voltage drop is 2V.
That is the source voltage 9V becomes 7V. Next, between the points D and E, the voltage drop is 4V. At this point, the voltage 7V becomes 3V. At last, between the points F and G, the voltage drop is 3V. At this point, the voltage 3V becomes 0V.
The portion of the circuit between the points G and H, there is no energy for the charge. So, it desires an energy boost for the passage through the external circuit again. This is provided by the power source as the charge passes from H to A.
Multiple voltage sources in series can be combined into a single source by summing their voltages, considering their polarity.
AC Voltage Sources in Series
In the case of AC voltage sources in series, the voltage sources can be added or combined together to form a single source provided that the angular frequency (ω) of the connected sources are identical. If the AC voltage sources connected in series are of different angular frequencies, it can be added together provided the current through the connected sources is the same.
Application of Voltage in Series Circuits
The application of voltages in series circuits include:
- Voltage divider.
- Fire alarm battery.
- Batteries in remote, toys etc.
- Lighting purposes in a train, Christmas tree etc.
