Physics

# The distance of a galaxy is $56 \times10^{25}m$. Assume the speed of light to be $3\times10^8 m s^{-1}$. Express order of magnitude of time taken by light travelled to the galaxy.

##### SOLUTION
We know that:

Time taken $= \dfrac { distance \ travelled }{ speed }$

So, time taken $= \dfrac { 56\times { 10 }^{ 25 }m }{ 3\times { 10 }^{ 8 }m{ s }^{ -1 } }$

So, the order is ${{18.6}\times { 10 }^{ 25-8 }s \ or \ 1.86\times { 10 }^{ 18 }s}$.

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Subjective Medium Published on 18th 08, 2020
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