MCQ
Suppose the sun expands so that its radius becomes $100$ times its present radius and its surface temperature becomes half of its present value. The total energy emitted by it then will increase by a factor of
- A$10^4$
- ✓$625$
- C$256$
- D$16$
✓
Answer
Correct option: B.
$625$
b
(b) $\frac{{{Q_2}}}{{{Q_1}}} = {\left( {\frac{{r_2^2}}{{r_1^2}}} \right)^2} \times {\left( {\frac{{{T_2}}}{{{T_1}}}} \right)^4}$$ = {\left( {\frac{{100}}{1}} \right)^2} \times {\left( {\frac{1}{2}} \right)^4} = 625$
(b) $\frac{{{Q_2}}}{{{Q_1}}} = {\left( {\frac{{r_2^2}}{{r_1^2}}} \right)^2} \times {\left( {\frac{{{T_2}}}{{{T_1}}}} \right)^4}$$ = {\left( {\frac{{100}}{1}} \right)^2} \times {\left( {\frac{1}{2}} \right)^4} = 625$
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