Have you ever wondered how a power plant makes electricity? It's pretty simple. A mechanical energy used for powering magnetic generators is transformed into electrical energy. Magnetic generator is basically a coil of wire that rotates between two magnets. Due to magnetic field between these two magnets electronsin the coil are propelled along the wire. As the coil keeps rotating, during one half of a turn, the electricity travels one direction through the coil. During other half, it travels other direction. One complete revolution of the coil is called a cycle. The number of such cycles in a second is called the frequency of the voltage or current. In this case alternating current.
Have you ever heard of protons, electrons and neutrons? They are tiny particles forming atoms. Atoms are only one- hundred-millionth of inch in diameter. Electrons have a negative charge. Protons and neutrons are made from smaller particles called quarks. Protons are made up of two quarks with 2/3 positive and one quark with 1/3 negative . So, protons are positive. They have the same sized charge as an electron only it is positive. Neutrons contain two quarks with 1/3 negative and one quark with 2/3 positive, so they are neutral. In an atom protons and neutrons form nucleus, the center of an atom. The nucleus has a positive charge. The negative electrons orbit around it. The atom is therefore electrically neutral. Ions
Sometimes an atom loses or gains an electron, when this happens it's called an ion. If it loses an electron then it gains a positive charge. If it gains an electron it gains a negative charge.
In some materials an electric charge flows better then others. Those materials are called conductor. Most of the conductors are different kinds of metals [copper, gold, silver, bronze, and steal]. Metal is a good conductor because they have a lot of free electrons in them. An insulator is the opposite of a conductor. It is hard for an electric charge to go through them. That's because the electrons inside them are tightly joined together in atoms, in simpler words the electrons are not free to move around.
There are two kinds of currents, direct current and alternating current. In our homes we have alternating current, but in batteries there is the direct current. When there is alternating current it flows back and forth very fast in an cable. Direct current goes only one direction in a cable or more likely in this case in a wire.