Current electricity or the constant flow of electric charges through a conducting material is the type of electricity we commonly utilize today. It powers our homes and most types of machinery, appliances or gadgets utilize it. There are two kinds of current electricity: direct current and alternating current.
1. Direct Current
A direct current is a unidirectional flow of electrical charges, and the most common mechanism that generates this kind of current electricity is the battery. Batteries directly generate electricity from the chemical reaction of the substances inside them. Another name for batteries is electrochemical cells. Each cell contains reacting substances and is divided into two parts or half-cells. Each half-cell has an electrode and an electrolyte.
In batteries, electrodes are solid electrically-conducting materials. Each battery has an anode which electrons flow into, and a cathode which electrons flow out of.
Electrolytes are types of substances whose electrons are easily dislodged. When an anode material comes in contact with an electrolyte, the loose electrons flow out of the electrolyte and into the anode. Conversely, when a cathode material touches an electrolyte substance, electrons flow out of the cathode and into the electrolyte.
A salt bridge is used to facilitate the flow of electrons from one anode half-cell to its corresponding cathode half-cell. Salt bridges are made from such materials that can pass on the electric current without absorbing the electrolyte substance it comes in contact with.
Once the battery is attached to an electronic device, the direct current flow is completed and electricity is generated and used.
2. Alternating Current
An alternating current is a flow of electrical charges that move back and forth. The most common mechanism that produces this kind of current electricity is the generator. Generators are basically made up of coiled copper wires and magnets. When the coiled copper wires rotate within the magnetic field generated by the magnets, alternating current is produced.
This is a rotating shaft around which the copper wires are tightly wound. The amount of electrical power produced by a generator largely depends on the number of coiled wires, the speed of the rotation of the armature and the strength of the magnetic field surrounding it.
The armature must constantly rotate to generate alternating current, and to do this it must be attached to another machine that will keep it rotating. This machine is called a turbine, and there are various designs depending on the kind of fuel used to power it.
Steam turbines use fossil fuels such as coal or oil to heat water and generate enough steam to turn the turbine. Wind turbines use strong air currents and are similar in concept to the windmill. Hydro electric turbines improve on the idea of the water-wheel and use the strong downward flow of water for power. Other fuel sources for turbines are geothermal energy, nuclear energy and the energy that comes from the constant movement of ocean waves.
Electricity as a form of energy can only be made from other forms such as mechanical energy, chemical, heat, light, etc. This is because of the limiting physical law that governs all forms of energy. It states that energy can neither be created nor destroyed but can only changed from one form to another.