This the third post in our series on the Four Fundamental Forces in the universe. If this post is the first you’ve read so far, check out these two as well:
In this post we’re going to explore the Electromagnetic Force and understand why it is essential to everything around us. We’ll break it up into two parts: The Electrostatic Force and the Magnetic Force. Enjoy!
The electromagnetic force is a force that occurs between electrically charged particles, such as electrons, and is described in electrostatics as being either positive or negative. Objects with opposite charges produces an attractive force between them, while objects with the same charge produce a repulsive force. Therefore, we have that the greater the charge, the greater the force and the greater the distance between the charged objects [Source].
This was further elaborated by physicist Charles Coulomb, which you might remember from Coulomb’s Law.
Ke is Coulomb’s constant, q1 and q2 are the magnitudes of the charges, and r is distant between the charges [Source].
Coulomb’s law quantifies the amount of force there is between two stationary (electrically) charged particles. The electric force between these two particles is what’s known as the electrostatic force. This attraction describes how protons (positively charged) in a nucleus and keep the orbiting electrons (negatively charged) from just leaving the atom. In other words, this is what keeps the atom together. There is a special particle that conveys this force – the photon. If you’re a bit unsure about what a photon is, check out these previous blog posts we’ve written on the topic [1, 2, 3].
Electrostatic force, as the name indicates, is a force where the charges are stationary (or at rest). A more technical explanation would be that a force exerted from one charged body on another (charged or uncharged), is an electrostatic force (Source). It is called static force because it can build up a charge in an object, thus creating a lot of potential energy, ready to travel from one place to the next. Just think of a balloon that you rub against your wool sweater. Here surface electrons from the wool sweater jumps over to the rubber balloon. If you’ve tried this at home, you’d see that the balloon would stick to your sweater after a while, which is because of the attractive force between them – the electrostatic force.
But this goes beyond the realm of balloons. Electrostatic force builds up in rain clouds as they rub together, and this excess negative charge is looking for protons to neutralize them. What are we talking about? Lightning!
So, this is a stream of electrons trying to find a positive place to land, and when electrons flow, they create a magnetic field.
A simple way to put it would be to say that the magnetic force is the reason why a magnet works the way it does. Although, it is important to know that while we look at the electrostatic force, the build up of charge, and the magnetic force, the magnetic field, they are in fact the same force – the electromagnetic force. As we remember, electromagnetism acts on objects with a charge, creating an electrostatic field around it that can either be positive or negative, while a magnetic field has both a positive and a negative pole. Magnetic poles work in the same way as charged particles in that opposite poles attract, and same poles repel each other. The magnetic force is, of course, carried between objects by photons, since it’s the same force. To understand how the electrostatic and magnetic force are in fact the same thing, let’s look at an example. If you have a coil of wire around a metal, with current passing through the wire, it generates a magnetic field, as we see in the gif below.
So how would this be in reverse? Could you generate electric current using a changing pattern of magnetism? Absolutely! If you use that same coil and put it in a magnetic field, and spin the wire (or the magnet), electricity would flow through the wire. This is the main reason why we have electricity today, and it’s generated this way through sources like wind, coal, nuclear, hydroelectric and more. The most common non-electromagnetic source of energy is solar power, but that’s a different story.
So there you have it, the main reason we have electric power and an essential ingredient in why the atom holds together. Stay tuned for our next, and final, fundamental force – gravitation. In the mean time, check out this youtube series, which has been an inspiration for this series. Check back soon!