Question

Two spheres of the same material have radii $1m$ and temperature $4000K$ and $2000K$, respectively. The energy radiated per second by the first sphere is greater than that by the second.

• A. True
• B. False

Answer 1

The correct option is B False

$\mu$ (energy radiated per unit time)

$=\sigma A{T}^4$

Where $A=$ surface area $=4\pi R^2$

$\mu \propto R^2{T}^4$

${\mu }_1=C\times 1^2(4000{)}^4$

$=256C\times (1000{)}^4$

${\mu }_2=4^{2}C(2000{)}^4$

$=64C\times (1000{)}^4$

Clearly ${\mu }_1>{\mu }_2$

$\therefore$ Energy radiation per second by the firms spheres is greater than by the sector.