Thermodynamics ** 4B40.40 ** Heat and the first law

Radiation

Two-can Radiation

WARNING: Be careful with the boiling water.

Equipment:

• Two cans, one black, one silver - shelf 6C
• kettle - shelf 6C
• two thermometers - shelf 6C
• or two thermocouple probes with meter - shelf 6C

Theory: The rate at which heat is radiated from an object depends on its emissivity. Black objects both absorb and emit heat at a higher rate than do shiny objects.

Description: Pour boiling water into both cans, filling them. Cap, and insert a thermometer into each through the cap. Monitor the temperature as the cans cool. The black can should cool significantly faster than the silver can.

Setup time: 10 minutes, including time for the water to boil.

References: (available in the demo room)

• Meiners, "Physics Demonstration Experiments", 38-5.1, p. 1176.
• Sutton, "Demonstration Experiments in Physics", H-156, p. 239.