A star is about 8 . 1 × 10 13 km from Earth. Assuming that the light travels at the speed 3 × 10 5 km / sec , find how long will light from the star take to reach Earth?

Given, Distance from Earth to the star = 8 . 1 × 10 13 km Speed of the light = 3 × 10 5 km / sec We know that, Time taken = Distance Speed Time taken = 8 . 1 × 10 13 km 3 × 10 5 km / sec Time taken = 8 . 1 2 . 7 × 10 13 km 3 1 × 10 5 km / sec Time taken = 2 . 7 × 10 13 - 8 sec a m ÷ a n = a m - n Time taken = 2 . 7 × 10 8 sec Hence, Light will take 2 . 7 × 10 8 sec to reach the Earth.

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Maths Hub (ICSE)>Chapter 5 - Exponents and Powers>Check Point>Q 7

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7th ICSE

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The mean distance of the moon from the earth is $384, 400, 000 m$ . Express the distance in the scientific notation.

Important Questions on Exponents and Powers

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7th ICSE

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Maths Hub (ICSE)>Chapter 5 - Exponents and Powers>Check Point>Q 8

The distance of the earth from the sun is $1, 49, 000, 000 k m .$ How long will the sun ray take to reach the earth, if it travels at $3.0 \times 10^{8} k m / s$ ?