Answer to Question #116583 in Physics for Habiba

Question

Q1) when a lamp is first on, it heats up. It then reaches a constant temperature. Explain why the temperature of the lamp remains constant?
Q2) on a sunny day a plastic bag is filled with cold water.Explain why the temperature of the water increases and then stays constant?

Answer 1

Q1. The temperature remains constant because the amount of heat energy generated by the lamp (incoming heat flow) equals the amount of energy radiated into the surroundings. If the incoming heat flow is higher, the lamp will heat up, if it is smaller than the radiation into the environment, it will cool down.

Q2. The same process is involved here. The sun heats the water up. The water heats up the surrounding air. When these flows reach equilibrium, the bottle stops heating.