Problem $2$

A spherical light bulb whose surface is maintained at a temperature of $70C$ is suspended in the middle of a room at $20C.$ The diameter of the light bulb is $5$ cm $.$ If the emissivity is $0\mathrm{.}8$ and convective heat transfer coefficient of the bulb is $15\frac{W}{m^2}-K,$ find the total rate of heat transfer from the bulb.