Question

Why are physical quantities expressed in the order of magnitude? Support your answer by an example.

Answer 1

Measurement of certain physical quantities is either too large or too small that these cannot be expressed conveniently. It is difficult to write or remember them. So such quantities can be expressed in the order of magnitude.
Example: The diameter of the sun is 1,390,000,000 m. It is difficult to write or remember such a measurement. So it is expressed as 1.39 × 109 m.
Here the power of ten i.e. 9 (i.e. exponent part of the measurement) gives the order of magnitude of the given quantity.
So the order of magnitude of the diameter of the sun is 10⁹ m.