0 votes

A solid sphere with an initial temperature $T{_1}$ is immersed in a large thermal reservoir of temperature $T{_0}$. The sphere reaches a steady temperature after a certain time $t{_1}$. If the radius of the sphere is doubled, the time required to reach steady-state will be

- $t{_1}/4$
- $t{_1}/2$
- $2{t_1}$
- $4{t_1}$