Light year is a unit of:
- time
- speed
- distance
- none of these
The Correct Option is C
Solution and Explanation
Light year is a unit of distance. More specifically, it is the unit of length used to measure the distance between astronomical objects.
According to a definition by International Astronomical Union (IAU), one light year is the distance that light can travel in one year in a vacuum. Light moves at a velocity of \(3\times {{10}^{8}}\,m/s\) . Thus, one light year is almost equivalent to 9.46 trillion kilometers (9.46 × 1012 Km). Light year is often used to measure the distance of stars.
The most commonly used unit to measure distance in astronomy is parsec. 1 parsec is approximately 3.26 light years.
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Questions Asked in AIIMS exam
Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R
Assertion (A) : 02 is liberated in the non-cyclic photophosphorylation.
Reason (R) : Liberation of oxygen is due to photolysis of water.
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Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R
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Reason (R) : Cro-Magnon man had slightly prognathous face.
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- Transcription
Concepts Used:
Units and Measurement
Unit:
A unit of a physical quantity is an arbitrarily chosen standard that is broadly acknowledged by the society and in terms of which other quantities of similar nature may be measured.
Measurement:
The process of measurement is basically a comparison process. To measure a physical quantity, we have to find out how many times a standard amount of that physical quantity is present in the quantity being measured. The number thus obtained is known as the magnitude and the standard chosen is called the unit of the physical quantity.
Read More: Fundamental and Derived Units of Measurement
System of Units:
- CGS system
- FPS system
- MKS system
- SI units
Types of Units:
Fundamental Units -
The units defined for the fundamental quantities are called fundamental units.
Derived Units -
The units of all other physical quantities which are derived from the fundamental units are called the derived units.