Tag Archives: Electricity

How does a clock run?

Many clocks and watches today are run by electricity.  But the most common type of clock, the spring or wind-up clock, is powered by the gradual uncoiling of a steel spring, which moves a series of gears, or wheels. The movement turns the hands that point to the hours and minutes on the clock’s face. …

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What is St. Elmo’s Fire?

St. Elmo’s Fire is the flash of light that is seen around ships in a thunder storm.  It is an electrical discharge caused by the storm. St. Elmo’s Fire is the name sailors have given to the sudden glow of ghostly flames that can sometimes be men flickering around ships in stormy weather. The “fire” …

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How are subway trains powered?

A subway is an electric railroad that runs under the ground.  Subways provide quick and cheap transportation in many big cities and help keep the streets free from traffic. Subway trains are made up of several cars that look very much like railroad cars.  Each car may hold 100 or more passengers. Subway trains run …

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What makes a railroad crossing signal go on?

Train crossing signals are worked automatically by electricity made to flow when the train’s wheels touch certain sets of rails near the crossing. People walking or riding need to be warned at an approaching train when they are about to cross the tacks on the highway. Safety gates may close.  Electrically operated waving arms and …

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How is our voice recorded on a tape recorder?

Tapes are recorded by printing magnetic patterns of sound on a special plastic tape. A tape recorder stores the sound of your voice on a thin, plastic tape that has been treated with a chemical so it can be magnetized. To make a tape recording of your voice, you speak into a microphone.  The microphone …

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How does a hydroelectric plant work?

Much of the electricity we use is produced by power plants located in huge dams.  Such plants, called hydroelectric plants, are run by the force of falling water. The water collects behind the dam.  It rushes down through an enclosed pipe and pushes against the blades are connected to a shaft which turns the generator. …

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