Dec 2020

Series & Parallel Circuits: Current VS Potential Differences

December 18, 2020

Did you know that physics is applied in most of the appliances you use daily? In our modern life, we are constantly using electricity and electronics, which is where you can find DC circuits! Some examples are phones, cars, TVs, calculators, and even lights!

And that’s why DC circuits is such an important concept to grasp in your JC physics tuition class. In this article, you will learn and understand the basic concepts of DC circuits, and the electrical quantities in them.

What is a DC Circuit?

A direct current (DC) circuit is a type of circuit with direct current flowing through. This means that the current only flows in one direction. DC circuits are generally found in electronic devices like flashlights, TV remotes, and also solar panels. Like any other electrical circuit, DC circuits can be described by three separate, but related electrical quantities – Current (I), Voltage (V), and Resistance (Ω).

What are the types of DC circuits?

DC circuits are classified into three types:

  • DC series circuit: In a series circuit, all the components are connected in one singular path. Thus, when one component breaks down, the whole circuit will burn out. An example of an object that uses series circuits is Christmas lights.
  • DC parallel circuit: In a parallel circuit, the components are linked with their corresponding ends joined together at common points to form separate and parallel paths. These paths are called branches. When a component breaks down, the other components will still function. Devices such as lamps, fans, and air conditioners, are connected in parallel to the main supply.
  • DC series-parallel circuit: Series-parallel circuit is a combination of both series and parallel circuits.

What is the difference between series and parallel circuits?

The significant difference between series and parallel circuits is the amount of current and potential difference across the circuit.

Current (I) is the rate of flow of charge. It can be measured using an ammeter which is placed in series with the component of interest in the circuit. In a series circuit, the amount of current flowing through each of the components are the same. However, in parallel circuits, the current flow is split between the components that are placed in parallel with each other.

Potential difference (V) is the work done per unit charge. However, unlike an ammeter, you must connect the voltmeter in parallel to measure the potential difference across a component in the circuit. In a series circuit, the total potential difference is shared between the components. On the other hand, the potential difference is the same across each loop in parallel circuits.

  • Series circuit: Vtotal= V1 + V2 + V3
  • Parallel circuit: Vtotal= V1 = V2 = V3

How are potential difference and current related?

According to Ohm’s Law, the potential difference across an ideal conductor is directly proportionate to the current flowing through it. The resistance of an electrical component can only be found by measuring the current and the potential difference across the circuit.

The equation that shows the relationship between current (I), potential difference (V) and resistance (R) is:

  • V = I × R


Understanding the concepts of DC circuits are important as they are applicable in your daily life, especially in the things we use. If you are interested in broadening your knowledge in this field of physics, Best Physics Tuition has fun and enriching tuition programs for O and A level students!

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