Units and Measurement
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Question : 31
Total: 33
The farthest objects in our Universe discovered by modern astronomers are so distant that light emitted by them takes billions of years to reach the Earth. These objects (known as quasars) have many puzzling features, which have not yet been satisfactorily explained. What is the distance in km of a quasar from which light takes 3.0 billion years to reach us?
Solution:
Time taken, t = 3 × 10 9
= 3 × 10 9 × 365 × 24 × 60 × 60 s
Velocity of light, c = 3 × 10 8 m s − 1
∴ = c t
= 3 × 10 8 × 3 × 10 9 × 365 × 24 × 3600 m = 2.84 × 10 25 m
= 2.84 × 10 22 k m
Velocity of light,
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