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Q:

# What is the speed of light in miles per hour?

A:

The speed of light in a vacuum is measured at 186,282 miles per second, which is 670,616,629 miles per hour. The speed of light is denoted mathematically by the symbol "c."

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Although early scientists thought that light traveled at an instantaneous speed, later experimentation concluded that there was a finite speed. Two French physicists in the mid-1800s, working simultaneously on different experiments, arrived independently at results that were within 1,000 miles per second of an accurate answer. It wasn't until 1879 when Prussian-born Albert Michelson, working in the United States, used a high-quality system of light beams, lenses and mirrors to arrive at the result of 186,355 miles per second, the most accurate measurement for the next 40 years.

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## Related Questions

• A:

The speed of light is about 670,616,629 mph, and one could travel round the earth 7 1/2 times in just a second with this speed. For another perspective, the average distance from the Earth to the Moon is 238,854 miles, and light travels this distance in just one second.

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• A:

The speed of light in mph (miles per hour) is 6.702 x 108 mph or more precisely 670,616,629 mph. In metric units, the speed of light in a vacuum is 2.998 x 108 m/sec.

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• A:

The speed of light when traveling through air is roughly 670,398,880 miles per hour. This number can be determined by dividing the speed of light in a vacuum by the index of refraction of air.