GK
PHYSICS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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time
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light
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distance
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intensity of light
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Detailed explanation-1: -A light-year is a unit of distance. It is the distance that light can travel in one year. Light moves at a velocity of about 300, 000 kilometers (km) each second. So in one year, it can travel about 10 trillion km.
Detailed explanation-2: -As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in a vacuum in one Julian year (365.25 days). Because it includes the time-measurement word “year", the term light-year is sometimes misinterpreted as a unit of time.
Detailed explanation-3: -Light is a form of energy, and can be measured in energy units (joules, calories) or in quantum units (quanta, einsteins).
Detailed explanation-4: -Parsec or parallactic second refers to the distance at which an arc of length equal to one astronomical unit subtends an angle of one second at a point. 1 parsec = 3 . 1 × 10 16 m = 3 . 26 light-years. 1 parsec is equivalent to 206265 AU and hence parsec is the largest unit of length.