Pupil sheet · Thermal radiation
Thermal radiation — return questions
Name ______________________ Date ____________
Use one to two weeks after the lessons. Keep the notes and the lesson closed.
1. state / explain
A hot-water tank stands in a cupboard at room temperature. (a) State whether the cupboard walls emit infrared radiation. (b) The owner wants to keep the water in the tank hot. Explain whether the outside of the tank should be dull black or shiny. (c) Supplement. The tank is replaced by a larger one with the same surface, kept at the same temperature. Explain what happens to the rate at which the tank emits radiation.
(a) The cupboard walls
(b) Dull black or shiny
(c) Supplement: a larger tank
2. state / explain
A car is parked in the sun all day. (a) State whether a black car or a white car absorbs more of the Sun’s radiation, and explain why. (b) Supplement. The car’s roof warms up in the morning, then stays at the same temperature all afternoon. Explain why. (c) Supplement. When the car is driven, its engine is cooled by a radiator made of thin metal tubes with fins. Identify two kinds of thermal energy transfer that carry energy from the hot coolant to the air.
(a) Black or white
(b) Supplement: a steady temperature
(c) Supplement: the radiator