WHY DO DOOR KNOBS FEEL COLD | THERMAL CONDUCTIVITY

In the wintertime, the door knobs feel really cold for no apparent reason! Why is that? Is there a science behind it? Or is it just a coincidence? Keep reading on to learn the science behind thermal conductivity of metals and how you can explain it to the kids.

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WHAT YOU WILL NEED

• 1 sheet of paper the size of your hand 
• 1 aluminium foil of the same size as the paper

HOW TO DEMONSTRATE HEAT CONDUCTION

Place the sheet of paper and aluminum foil flat on a table. 

Place one hand flat on the sheet of paper and another flat on the foil sheet. Is one surface cooler than the other? 

Can you explain, why ?

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THERMAL CONDUCTIVITY OF METALS

Metal objects are generally regarded to be colder than wood, but this may not actually be the case; in fact, metal door knob are likely to be the same temperature as the wooden door. Their chilliness is caused in part by how easily they conduct heat away from your hand when touched.

Metals are excellent heat conductors, so when you touch a metal object, heat easily transfers from your hand to the metal. Because wood and plastic are poor conductors of heat, they do not conduct as much heat as metal objects. As a result, they are relatively warm to the touch.

This is just one example of heat or thermal conduction. Heat is transferred when two objects of different temperatures come into contact with each other. Holding a hot cup of coffee with cold hands, for example, gradually warms your hands. So, the next time you touch something and feel a cold or hot temperature, you’ll know whether or not the material is a good heat conductor.

We hope you learned something new about thermal conductivity of metals as a result of this post!

If you enjoyed this activity and are looking for more science experiments, we recommend investigating how to make a plastic toy car or, take a look at how fidget spinners work.

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