Relevant Resource questions :

Concepts demonstrated :

• Thermal capacity of materials
• Heat flow
• Specific heat
• Conduction

Equipment needed :

• Box which contains three large A1 bars, nine small thin plates of different materials and insulating material.

• Cool one A1 bar in a freezer for several hours.
• Heat one A1 bar in boiling water for 15 minutes.
• Leave the third Al bar at room temperature.
• Place three bars with their respective temperatures at the bottom of the box.
• Place nine plates (three copper plates, three stainless steel plates and three perspex plates) on the nine spaces so that one of each plate is on each temperature.

• None (see Other Comments)

Discuss the thermal conduction of different materials.

How to use the Demonstration :

• Get students to touch two of the plates at a time, one with each hand, without looking at the plates.
• Have them estimate the temperature. Repeat for other combinations of plates.
• Take a class average. Temperatues may typically be -2degC, 20degC and 50degC but students may come up with all sorts of wild values.
• Discuss why their estimates were so wild i.e. develop the concept of thermal capacity of various materials.
• Variations to this experiment might include blindfolding students and asking them to compare objects they are touching. Ask the students to explain their results when they see what they have touched.

• Car seat belt and belt buckle on a hot day.

• House in a wooden box so that the demonstration is easily portable.

• A poster for Open Days would be good - telling people what to do "but not saying what to expect".
• Best used in a tutorial not a lecture.
• It may be worth constructing some test squares using a composite material. Perhaps one with a honeycomb structure.