1. The problem statement, all variables and given/known data This is not exactly homework, but is homework level so this is probably the best place to ask rather than the more learned sections. However, I'm prepared to defer to your better judgement. I want to put a web camera inside a foam ball. The camera is a retail product so it's passed relevant EU safety standards. My concern is will heat build up cause the foam to melt, or burn my house down by starting a fire. The camera runs off 5V DC consuming approximately 500mA. The hollow sphere is of outside diameter 300mm with a wall thickness of 20mm. I would characterise this as a thin walled vessel. The sphere's made of expanded polystyrene /Styrofoam. This is all the data I know for certain. What will the temperature rise be inside the sphere above ambient? 2. Relevant equations As this is a safety issue, I'm not giving any equations that I have used. I do not want to influence /prejudice anyone's thinking. I'd very much welcome an independent assessment. 3. The attempt at a solution I've considered the thermal conductivity of the material, the power dissipation of the camera and the sphere's mean surface area. I've also assumed that the thermal conductance through the camera's mounting to the outside is negligible. I've calculated a 7 degree rise inside the sphere. I deem this acceptable but what do you think?