1. The problem statement, all variables and given/known data Two rooms, each a cube 4.0m on a side, sare a 12cm thick brick wall. Because of a number of 100-W light-bulbs in one room the air is at 30 Celsius, while in the other room it is at 10 Celsius. How many of the 100-W light-bulbs are needed to maintain the temperature difference across the wall? 2. Relevant equations I'm not so sure if this equation would work. But I have tried using it. ΔQ/Δt = (kA(T-T))/l 3. The attempt at a solution I used the above equation and got 213.3 J/s. But I do not know if I am going the rigt direction. The answer that the book gave is 22 bulbs. Please help me and explain how I can solve this.