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प्रश्न
The distance of a galaxy is of the order of 1025 m. Calculate the order of magnitude of time taken by light to reach us from the galaxy.
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उत्तर
According to the problem, the distance of the galaxy = 1025 m.
Thus, the required time = `"Distance"/"Speed"`
⇒ `10^25/(3 xx 10^8)` sec
= `1/3 xx 10^17` seconds
Required time = `10/3 xx 10^16`
= 3.33 × 1016 seconds.
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संबंधित प्रश्न
Just as precise measurements are necessary in science, it is equally important to be able to make rough estimates of quantities using rudimentary ideas and common observations. Think of ways by which you can estimate the following (where an estimate is difficult to obtain, try to get an upper bound on the quantity):-
the number of air molecules in your classroom.
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- length
- time and
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Write their names and symbols.
Match the following.
| Column A | Column B |
| (1) Length | a. kilogram |
| (2) Mass | b. cubic metre |
| (3) Area | c. metre |
| (4) Volume | d. square metre |
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- Liquids are measured with this physical quantity.
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