Question 361: Properties of Matter

Question

Assuming the sun to have a spherical outer surface of radius r, radiating like a black body at temperature toC, the power received by a unit surface, (normal to the incident rays) at a distance R from the centre of the sun is 
where $$\sigma $$ is the Stefan's constant.

Accepted Answer

Power radiated by the sun at tÃÂ°C
$$ = \sigma {\left( {t + 273} \right)^4}4\pi {r^2}$$
Power received by a unit surface
$$ = {{\sigma {{\left( {t + 273} \right)}^4}4\pi {r^2}} \over {4\pi {R^2}}} = {{{r^2}\sigma {{\left( {t + 273} \right)}^4}} \over {{R^2}}}$$

Answer

$${{{r^2}\sigma {{\left( {t + 273} \right)}^4}} \over {4\pi {R^2}}}$$

Answer

$${{16{\pi ^2}{r^2}\sigma {t^4}} \over {{R^2}}}$$

Answer

$${{{r^2}\sigma {{\left( {t + 273} \right)}^4}} \over {{R^2}}}$$

Answer

$${{4\pi {r^2}\sigma {t^4}} \over {{R^2}}}$$

Properties of Matter

Assuming the sun to have a spherical outer surface of radius r, radiating like a black body at temperature toC, the power received by a unit surface, (normal to the incident rays) at a distance R from the centre of the sun is where $\sigma $ is the Stefan's constant.

Choose the correct answer: