Three stars, labelled A, B and C, have the following luminous powers (total energy…

PHYSICS · Multi-part · CBSE · Physics · Units and Measurements · Units and Measurements

Problem

Three stars, labelled A, B and C, have the following luminous powers (total energy radiated per second): Star A:

3.85\times10^{26}\,\text{W}

Star B:

2.30\times10^{31}\,\text{W}

Star C:

6.0\times10^{18}\,\text{W}

(i) Arrange the stars in ascending order of their luminous power and write the order of magnitude for each. (ii) Calculate how many times more luminous Star B is than Star A. Express the factor as

a\times10^{n}

with

1\le a<10

. (iii) If an artificial satellite requires

4.0\times10^{3}\,\text{W}

to operate, determine the factor by which the luminosity of Star C exceeds this requirement. (iv) Comment, with numerical support, on whether Star C can be considered faint or bright compared with the other two stars.

Related theory

Measurement Systems
Significant figures and magnitude
Significant figures and rounding

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