The speed of light in air is `3.00xx 10^8 m//s` The distance travelled by light in one year `(i.e.365 days = 3.154xx10^7s)` is know as one light year. A student calculates one light year = `9.462xx10^(15)`m. Do you agree with the student ? If not what should be the correct value of one light year?

Explanation

We know, that one light year = speed of light`xx`
time (one year)
`=(3.00xx10^8)xx(3.154xx10^7)`
`= 9.462xx10^(15)m`
As per rule, when tow physical quantites are multiplied, the number of significant figures in
the result cannot be greater then the least number
of significant figures in any of the tw quantites.
We do not agree with the student. The product
is, therefore, rounded of to contain three
significant figures. We may wirte :
one light year `= 9.46xx10^(15)m.`