What is the Strong Force ?

The strong force is the strongest force out of all of the four fundamental forces! It is the attractive force that keeps the repelling protons together in a nucleus. However, the strong force only works over a very, very, very small distance (0.000000000000001 m or 1 x 10-15 m). This distance is the average distance that an atom's nucleus covers.

First of all, we need to know that like charges repel and opposite charges attract. The nucleus is made up of neutrons and protons. Neutrons have no charge. Protons, however, are positive and because they are all positive they want to repel from each other. The only thing that keeps them together is the strong force. If the strong force didn't exist, there would be nothing but hydrogen and neutrons floating in space. Look at the picture below. The positive particles are protons (purple) and the other ones are neutrons (blue). When the protons and neutrons are apart there is no strong force but when they are together to resemble a nucleus, the strong force is in action. You should also know that the reason the protons and neutrons are pulled together is not because of the strong force.

Like charges repel and unlike charges attract ?

Magnets are composed of north poles and south poles. One can think of a north pole as being a positive charge and a south pole as a negative charge. North poles attract south poles like positive charges attract negative charges. Furthermore, like poles repel as like charges repel. But, there is a difference; you can never get a magnet with just a north pole or just a south pole. Even if the magnet is broken up into many tiny pieces, EVERY piece will have a north pole and a south pole.

When two like poles are pushed together, they usually flip over so that the north pole and south pole come together. Like poles repel (like “charges” repel) and unlike poles (unlike “charges”) attract.