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Skip to 0 minutes and 0 seconds In this video we’re going to investigate the forces between charges. Welcome to Electrify week one.

Skip to 0 minutes and 11 seconds We’re going to look at a situation where we’ve got two challenges. We have a black negative charge and a red positive charge. And you can also see the symbols in the centres of them. If we just put them next to each other and let go, what will happen to them? Well, they’re going to be attracted to each other. We can see them moving. And we can also represent this with some blue arrows. These arrows represent the overall force that we’re going to quantify. And we’re interested in the total result.

Skip to 0 minutes and 44 seconds This time the charges are further apart. We know this positive and negative charge will be attracted to each other. But will that force– that arrow– get larger or smaller?

Skip to 0 minutes and 57 seconds So we can see them moving together. But this time the attractive force between the charges is smaller.

Skip to 1 minute and 8 seconds Now we have two positive charges. In this situation, if we just let them go, what’s going to happen to them? Well, they’ll repel. So they’ll want to move further away from each other.

Skip to 1 minute and 26 seconds This time we’ve got a positive charge and a negative charge. But a larger circle represents a larger charge. So we have a much larger magnitude negative charge. What’s going to happen? Will the force get larger or smaller?

Skip to 1 minute and 44 seconds Overall, the force is larger. And what we’re interested in is the fact that the large negative charge will exert a big charge on the smaller, positive charge. And we can see this with the arrows. This is a similar situation to gravitational potential energy, which you may have looked at in school.

Forces between charges

Charges are the most fundamental building blocks of electricity. You will see later in the module that we can think of other electrical properties, such as voltage and current, in terms of the build-up and movement of electrical charges. This first video presentation considers an even more basic concept, the force that arises between charges. Understanding these forces is a key aspect of understanding electromechanics.

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This video is from the free online course:

Electrify: An Introduction to Electrical and Electronic Engineering

University of Liverpool