Welcome to Common Core Texts, a project by Michael DeJoseph. Here you'll find high-quality reading passages for grades 3 to 12 in ELA, Social Studies, History, Science, Technology, Engineering and Math (STEM) and many other topics.

A Bright Idea
A Reading Comprehension Passage by Common Core Texts

Most of us don’t have to worry very much about the safety of our water. We turn on the faucet and, like magic, out flows clean pure water. But what if you find yourself far from the comforts of home? For example, you might be camping in the woods. Or you may be traveling in a country that lacks clean water. How would you find water that is safe to drink?

One ingenious solution is to use an ultraviolet (UV) light purifier. These neat devices are small enough to fit in your pocket and powerful enough to clean a gallon of water at a time. A UV purifier contains a special light bulb at the end of a pen-shaped device. This tiny bulb sits behind a clear waterproof cover. Using it is easy: you simply dip the device into your bottle of water and stir.

Ultraviolet light has a shorter wavelength than visible light. When its powerful rays shine on germs, they cause the chemical bonds that hold the germs together to break apart. That is why UV light purifiers are able to kill the viruses and bacteria that make water unsafe to drink.

However, UV purifiers aren’t a one-size-fits-all solution. The ultraviolet rays need to reach germs in order to kill them. That means that cloudy water cannot be purified using ultraviolet light. A UV purifier only works on water that is free of dirt and debris.

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