Voltage in Series

When two or more electrical components are connected together in a chain-like arrangement, then such a circuit is known as a series connection or series circuit.

What are Voltages in Series?

There is only a single way for the charge to pass through the series circuit. Voltage can be defined as the variation in potential in charge across two points in an electrical circuit. We will discuss in detail about the voltages in a series circuit in this article.

As we know, the potential difference across the ends of any external circuit is produced because of the battery in a circuit that delivers energy for the charge to pass through it. Now, to understand the voltage drop, let us assume that a potential difference of 5 volts is generated by a cell of 5 volts across the external circuit.

Now, at the positive terminal, the value of electric potential is 5 volts greater than the negative terminal. Therefore, the charge causes a loss of 5 volts in electrical potential when it flows from the positive terminal to the negative terminal and this drop in the potential or loss in the potential is known as voltage drop. Voltage drop generally happens when the electrical energy of the charge is transformed into some other form of energy while passing through different components in the circuit.

Again, if we consider a circuit that is powered with a 6 Volt cell and with more than one resistor connected in series, then there will be some voltage drop in each resistor connected, and the total loss of electrical potential is 6 V. But if we calculate the sum of the voltage drop of all the components, then it will be 6 V which is equal to the voltage rating of the power source.

Mathematically it can be expressed as:

ΔV_Battery = ΔV₁ + ΔV₂ + ΔV₃ +…….

Individual voltage drop can be calculated using Ohm’s law as:

ΔV₁ = I x R₁

ΔV₂ = I x R₂

ΔV₃ = I x R₃

To understand this concept deeply:

Let us assume a series circuit powered by a 9V energy source, and it includes three resistors connected in series. During the passage of current throughout the series circuit, we are going to find out the potential difference at different locations.

The positions are marked in red in the circuit diagram given below. As we know, electric current always flows from the positive terminal towards the negative terminal of the power source. The loss in potential due to the resistor can be represented by the negative sign of the voltage or potential difference. The diagram named the electric potential diagram that is shown in the given figure helps us to find the potential difference between different points in the circuit.

This example shows that the electrical potential at H is equal to 0V because it is the negative terminal, and at A, the electric potential is 9V because it is the positive or higher potential terminal. The charge gains 9V of electrical potential when the current passes through the 9V power source, that is, from point H to A. On the other hand, the charge drops this 9V completely when the current passes all over the external circuit.

This process happens in three steps; that is, when the current passes through the resistors, there will be a voltage drop, but when the passage is through the mere wire, then no voltage drop occurs. So, between the points AB, CD, EF and GH, we can see that there is no voltage drop. But the voltage drop is 2V between points C and B. This clearly means that the voltage source of 9V will become 7V.

Next, between the points E and D, the voltage of 7V becomes 3V because the drop in voltage will be 4V. In the end, between the points G and F, the drop in voltage is 3V. This means that at this point, the voltage becomes 0V.

There is no energy for the charge at the portion of the circuit between the points H and G. Therefore, for the passage of current through the external circuit again, it needs an energy boost, which is supplied by the power source as the charge passes from point H to A. A single voltage source can replace several voltage sources in series by taking the sum total of all the voltage sources, but polarity between them is considered too.

Resistance and Ohm’s Law:

Conclusion for Voltage Across Components in a Series Circuit

• In a series circuit, the supplied voltage will be shared among components.
• In a series circuit, the sum of the voltages across components is equal to the supply voltage.
• In a series circuit, the voltages across each of the components are in a similar proportion to their resistances. This means that the supply voltage divides equally if two similar components are connected in series.

Application of Voltage in Series Circuits

Following are some applications of voltages in series circuits:

• Battery of fire alarm
• Voltage divider
• Batteries in toys, TV remote etc.
• Lighting purposes

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