Answer:
A signal is sent from a nerve cell to a muscle cell
Explanation:
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Answer:
Light refracts whenever it travels at an angle into a substance with a different refractive index (optical density). This change of direction is caused by a change in speed. When light travels from air into water, it slows down, causing it to change direction slightly. This change of direction is called refraction
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Answer:
Wells can dry up or become contaminated, this question isn't really clear so it's hard to say. It can become contaminated by underlying salt water, heavy metals, or man-made pollutants. Wells also dry up frequently and become unusable.
