Physics - Heat & Thermo Question with Solution | TestHub

A highly conducting uniform sphere of thermal capacity C is heated by an electric heater, a resistance R fitted within the sphere. A constant current I is passed through the heater starting at time $\mathrm{t}=0$ which gives constant power. The sphere loses heat at a rate equal to k times the temperature difference between the sphere and the surrounding. The initial temperature of the sphere and that of the surrounding is 0°C. The time at which sphere attains half of its maximum attainable temperature is $\frac{\mathrm{c}}{\mathrm{k}}\ln 2^{\mathrm{a}}$. Then find the value of "a".