Fridges
How does a fridge make things cool?
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  Facts
  • A fridge works by taking away heat energy away from things inside the fridge which cools them down.
  • At the back of the fridge thereís a tube arranged in a coil that runs in a circuit into the fridge then back out again.
  • Inside the tube is a liquid chemical called a refrigerant.
  • When the tube goes inside the fridge the refrigerant chemical turns into a gas, which absorbs the heat energy around it. Then, when the refrigerant travels through the tube to the outside of the fridge it changes back into a liquid and the heat energy is released into the air.
  • Thatís why the back of your fridge feels warm and the inside feels cold.
 
  Did You Know?
  • A fridge uses evaporation to absorb heat from the fridge.
  • The first refrigerator was made in the 1920ís - about 80 years ago.
  • Before that people used to store their food in cool places around the house. Like on the shady, breezy side of the house in a box that had holes in it to let the air circulate and they called it a "safe".
  • Some people bought huge blocks of ice to try and keep food cool and fresh. This worked well until the ice melted away!
 
  Experiments
Move heat
Next time youíre helping with the dishes ask if you can conduct this experiment.

What you need:
Some ice cubes
A plastic container (clean empty ice cream container)
A spoon straight from the wash.

What you do:
Put the ice cubes in the plastic container. Put a spoon in with the ice cubes as soon is it comes out from the sink being washed in fairly hot water.
Notice how hot the spoon is as you put it into the container with the ice cubes. Leave it in there for a minute pick up the spoon and check if the temperature has changed. Is the spoon still hot? Is any of the spoon still warm?
Metal is a conductor - itís very good at moving energy, like heat and/or cold.
 
  Investigation
Look at the dairy products in your fridge. What is the recommended temperature they should be stored at?
Your fridge should be about 4 degrees Celsius all the time. Use a weather thermometer (not a human temperature thermometer) to measure the temperature in your fridge.
Ask an adult to help you with this investigation.
Put a small drop of perfume or nail polish remover on the back of your hand. Is it a liquid or a gas? What happens to the liquid? What does it feel like? How is it similar to how a fridge works?
 
  Jokes
What do you get if you cross a fridge with a radio?
Cool music!
From Daniel
 




 
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