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- Describe experiments to demonstrate the properties of good and bad conductors of heat.
One experiment is the wax method:
Take rods of different materials with the same dimensions (same length and cross-sectional area), and attach a drawing pin to the end of each using the same mass of wax.
Using a container with four rubber-lined holes in the side. Insert the rods through the holes, pushing them in the same amount. Fill the container with boiling water and start the stopwatch. Time how long it takes the drawing pin to fall off each rod and compare the times. The rod that allowed the pin to fall off fastest is the best conductor.
Another experiment can show us how good a conductor of thermal energy water is this:
- Explain heat transfer in solids in terms of molecular motion.
According to the kinetic theory, all materials are made up of tiny, moving particles. In solids, these particles tend to vibrate around a fixed spot.
When you apply heat energy to these particles, they tend to vibrate more vigorously.
This heat energy can be transferred from one end of the material to the other, because the particles with more energy collide with the adjacent particles, causing them to vibrate harder and so forth.
In other words, the particles with more thermal energy pass on their energy to the particles surrounding them, causing the heat to spread from the hotter regions to the colder regions of the material.
This process is called conduction.
Notes submitted by Sarah
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