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All experiments show that light travels at a constant velocity through a vacuum, and that more importantly that this speed is finite, and that nothing travels faster than light. The speed of light is approximately 300,000,000 metres per second. A light year is the distance light will travel in one year, and this distance—using the above approximation—is 9,460,800,000,000,000 metres in one year. This is equivalent to 5,913,000,000,000 miles.
White light is a mixture of light of different colours, each colour having its own wavelength. The extreme red end of the visible spectrum has a wavelength of 0.4 millionths of a metre and violet at the other end 0.8 millionth of a metre. Since the velocity v of all radiation corresponds to the equation v = n where n is a constant it will be clear that light of different colour travels at different speeds. AA
See also astronomy; relativity. |
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