Electricity is the flow of electrical power or charge. It is a secondary energy source because it is converted from another (primary) source of energy, such as coal, natural gas, oil, nuclear or renewable sources. Electricity can be made from either renewable or non-renewable energy sources, but it is neither renewable nor non-renewable since it is a secondary source.

Electricity has grown in technological leaps and bounds ever since 1752, when Benjamin Franklin flew a kite with a metal key tied to the string during a thunderstorm to prove that lightning was electric.

Today, it is a necessary component to our fast-moving society.

How Electricity Works

Everything we touch is made up of matter, and matter is made up of tiny “building blocks” of atoms. Within the atoms are even smaller, electrically charged particles called electrons. The movement of the electrons creates electricity. Electrons transmit an electrical charge through solid matter (such as metal) to produce an electrical current. The number of electrons moving in an electrical circuit is called “amperage,” or current, measured in amps. The pressure pushing the electrons is “voltage,” measured in volts. Electricity travels at the speed of light, more than 186,000 miles (299,338 kilometers) per second.

And how is electricity moved from where it is created to where people need to use it? Transformers (electric devices that move electric energy from one set of circuits to another) are used to efficiently transmit electricity over long distances. This makes it possible to supply electricity to homes and businesses located far from an electric generating plant. The electricity produced by a generator travels along cables to a transformer, which changes electricity from low voltage to high voltage. Transmission lines are used to carry the electricity to a substation. Substations have transformers that change the high-voltage electricity into lower-voltage electricity. From the substation, distribution lines carry the electricity to homes and buildings that require low-voltage electricity.

All sources of electricity must have a positive terminal and a negative terminal, and electrons will always flow from the negative to the positive through a conductor (copper wire, for example).


Lightning generates plenty of electricity. It starts as electrical charges developing inside a cloud. The positively and negatively charged atoms go to different parts of the cloud—the positive at the top, negative at the bottom. When the negatively charged atoms get too crowded, they “jump” to a different cloud or even to the ground: that “jump” causes a spark of static electricity called lightning.

Even though lightning produces electricity, it’s not practical to use that electricity for our power needs. There are too many obstacles—we don’t know when or where lightning will strike, how powerful each bolt will be or how to direct the surge of electricity into our electrical systems. What’s more, the average lightning bolt produces about 250 kilowatt hours of electricity, but the average home uses 936 kilowatt hours of electricity every month. That means that one lightning bolt’s energy could only power one home for about nine days!

Static Electricity

Have you ever reached for a metal doorknob and gotten a shock? That was static electricity at work! But how does that happen?

All matter is made up of atoms that contain protons, neutrons and electrons. Protons have a positive charge, electrons have a negative charge, and neutrons have no charge. Atoms normally have the same number of protons and electrons, and in this state, the atom is “neutral.” But by rubbing things together, you can make electrons move from one atom to another, causing atoms to have a positive or negative charge. That’s static electricity!

So when you walk across a carpet, electrons move from the carpet to you, giving you extra electrons. Then when you touch a doorknob, the electrons move from you to the knob—and you get a static electric shock.

History of Electricity

Electricity has grown in technological leaps and bounds ever since 1752, when Benjamin Franklin flew a kite with a metal key tied to the string during a thunderstorm to prove that lightning was electric. Today, it is a necessary component to our fast-moving society.

1752 – Benjamin Franklin flew a kite with a metal key tied to the string during a thunderstorm to prove that lightning was electric.

1800s – Italian scientist Alessandro Volta created the first electric cell battery by soaking paper in salt water, placing zinc and copper on opposite sides of the paper and examining the electric current produced in the chemical reaction.

English scientists William Nicholson and Sir Anthony Carlisle discovered that applying electric current to water produced hydrogen and oxygen gases. This process was later termed “electrolysis.”

English scientist Michael Faraday discovered that an electric current could be created by passing a magnet through a copper wire.

1838 – The fuel cell effect, combining hydrogen and oxygen gases to produce water and an electric current, was discovered by Swiss chemist Christian Friedrich Schoenbein.

1876 – William Grylls Adams and Richard Evans Day discovered that selenium produces electricity when exposed to light. Although selenium solar cells fail to convert enough sunlight to power electrical equipment, they prove that a solid material can change light into electricity without heat or moving parts.

1879 – American inventor Thomas Edison produced a reliable, long-lasting electric light bulb in his laboratory.

1880 – By the end of the 1880s, small electrical stations based on Edison’s designs were in a number of US cities. But each station was able to power only a few city blocks.

In the late-1800s, Nikola Tesla created the transformer to transport electricity over long distances. Tesla’s inventions brought electricity to light the inside of our homes and to power industrial machines.

1882 – Thomas Edison built the first practical coal-fired electric generating station, supplying electricity to some residents of New York City using a direct current (DC) system.

1886 – About 45 water-powered electric plants were open in the US and Canada.

1887 – Heinrich Hertz discovered that ultraviolet light alters the lowest voltage capable of causing a spark to jump between two metal electrodes.

1895 – Using the newly discovered alternating current (AC) power system, George Westinghouse opened the first major power plant at Niagara Falls. This AC plant could transport electricity more than 200 miles.

Uses for Electricity

If you’ve ever lost power in a thunderstorm, you’ve probably noticed how many items in your home use electricity. But the uses for electricity go way beyond your TV—electricity is used in all kinds of useful ways, including:

  • Airplane and car navigation systems
  • Streetcars and subways
  • Pacemakers that help regulate people’s heartbeats
  • Refrigerators, dishwashers and most other home appliances

Demand for Electricity

Although the current recession is expected to dampen electricity demand in the near term, electricity demand is expected to increase by 77% by 2030 (source: Energy Information Administration / International Energy Outlook 2009). This growth projection is based on population growth and increased supply to currently non-developed countries.

Electricity Around the World

According to a 2009 report by the U.N. Development Programme, 1.5 billion people—a quarter of the world’s population—live without access to electricity. This problem is worst in Africa, where entire nations have no power. In 11 African countries, more than 90% of the population has no electricity. Many of these Third World countries without electricity also lack the government infrastructure needed to make nationwide electricity access a reality.