# GATE2012-15

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
1. t${_1}$/4
2. t${_1}$/2
3. 2${t_1}$
4. 4${t_1}$