Have you ever noticed how many things we tend to take for granted? When we wake up in the morning and head to the bathroom to get ready for school, we don't give much thought to how we'll see in the dark. We just take it for granted that we'll flip the light switch and, like magic, the lights will come on!

But have you ever thought about how many things have to happen for those lights to come on when you flip that switch? For starters, you have to have electricity flowing to the outlets and switches in your house.

Where does the electricity you use come from? There are many different ways to produce electricity. Some people have electricity generated by power plants that burn coal. Others might get their electricity from wind turbines.

Still others who live near rivers may get their electricity from an entirely different source. What are we talking about? Hydroelectricity, of course!

Hydroelectric power is generated by flowing water. If you live near a river that has dams, you might very well benefit from hydroelectricity. So just how does a dam convert flowing water into electricity?

It's actually fairly simple and straightforward. Hydroelectric and coal power plants produce electricity in a similar way. Both use a power source to turn the propellers of a machine called a turbine. As the turbine spins, it turns a metal shaft connected an electric generator, which is basically a motor that produces electricity.

In the case of a hydroelectric dam, it's flowing water that's used as the power source to turn the turbine. Hydroelectric dams are constructed with a special passageway — called the penstock — for water. These passages are sloped downward to create a flow of falling water.

As the water falls down the passageway, it's directed past the propellers of the turbine. The force of the flowing water turns the turbine, which in turn spins the metal shaft in the electric generator that produces electricity!

But why are dams necessary? Could you just construct a hydroelectric plant on any river? Not exactly. Hydroelectric dams need to be constructed on large rivers that have a large drop in elevation. The dam stores water that can then be controlled by engineers to regulate the water flow to produce electricity on demand at a specific rate.

Unlike coal, which is burned to produce steam to turn the turbines in a coal power plant, the water used in hydroelectric dams keeps flowing. Thanks to the natural water cycle, hydroelectric power plants take advantage of an easily renewable energy source!

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