David has taught Honors Physics, AP Physics, IB Physics and general science courses. He has a Masters in Education, and a Bachelors in Physics.
After completing this lesson, you will be able to explain what an electric circuit it, how energy transfers in a circuit, and how circuits relate to the conservation of energy. A short quiz will follow.
What Is an Electric Circuit?
Circuits are everywhere in modern life: lights, TVs, computers, washing machines, air conditioning, you name it. Life would be totally different if we didn't have circuits. But what exactly is a circuit? Put simply, an electric circuit is a complete loop where electricity is flowing, to power components in that loop. And electricity is the continuous flow of electrons.
Relationship of Energy and Electric Circuits
On a basic level, electric circuits transfer energy. If they didn't, none of our electrical devices would even work. How could a light bulb produce light energy if it wasn't given that energy from the electricity we supply to it? How could the motor in a tumble dryer turn with mechanical energy if that didn't come from somewhere? Electrical energy is a particular type of energy contained within an electric current, flowing around a circuit.
When you roll a ball down a hill, gravitational potential energy is changed into kinetic, or movement, energy. Circuits work in a similar way: The battery provides a difference in electric potential energy between the two terminals, the positive and negative sides of the battery. Then, if you connect those two sides of a battery in a circuit loop, charges have to flow, just like how the ball has to roll down the hill. This is why a circuit works in the first place.
Conservation of Energy
Another thing we understand about energy is that it's always conserved. Conservation of energy says that energy is neither created nor destroyed, it only moves from one type to another, or one place to another. But how does this work in terms of circuits?