Final answer:
The question relates to the thermal effects of a lightbulb inside a concrete box. Due to lack of necessary data, it's impossible to calculate the exact air temperature increase inside the box.
Step-by-step explanation:
The question concerns the heat transfer through conduction and the effect of a lightbulb's heat on the temperature of air inside a sealed concrete box. However, the actual values and specific characteristics of the lightbulb and box (like the thickness of the concrete wall or the power rating of the lightbulb) are not provided, making it impossible to calculate a precise answer.
Normally, to calculate the air temperature inside the box when the lightbulb is on, one would need to know the power of the lightbulb, the properties of the concrete, and the size of the box. Given the lack of sufficient information, it is not possible to accurately calculate the air temperature inside the box. Instead, we can infer generally that when the lightbulb is on, it will generate heat and the temperature inside the box is likely to increase above the surrounding air temperature of 20°C, but without specifics, that is as detailed as the answer can get.