Heat

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Heat
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What is heat?
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• A form of energy.

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What is temperature
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A scale used to measure heat energy (how hot or
cold something is).
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What would you use to measure how hot or cold
something is?What is the unit of measurement?
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A thermometer The unit is Degrees Celcius (oC)
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Complete the table to show the type of heat
transfer for each physical state?
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Physical State Method of Heat Transfer
Solid
Liquid
Gas
Conduction Convection Convection
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What type of heat transfer is being described?
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Conduction

• The end particle (1) gets hot, vibrates and
  passes some of its heat to the next particle (2)
• This particle (2) becomes hot, vibrates and
  passes some of its heat to the next particle (3)
• This process is carried along the line of
  particles

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What type of heat transfer is shown here?
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Convection (of liquids)
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Why does smoke from the wooden taper get drawn
into the box and then out of the chimney?
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Convection (of gases)
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What is convection?
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A type of heat transfer where hot particles
rise and cold particles fall.
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What do you call a material that allows heat to
pass through it easily?
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Conductor
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What do you call a material that DOES NOT allow
heat to pass through it easily?
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Insulator
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Which type of metal will melt the wax first? Why?
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Hot Water
The copper will melt the wax first because it is
the best conductor of heat
Copper Brass Mild steel Stainless steel
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How is heat transfer used to boil water in this
kettle?
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• CONVECTION
• (The element heats the water at the bottom.
• The hot water is less dense and rises up
• The cold water is more dense and falls down to
  the bottom and meets the element
• This goes on in a cycle until the water is
  boiling)

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Who will get hot first?
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The metal is the best conductor of heat. The
wood and polystyrene are good insulators
Polystyrene
Heater
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How does double glazing cut down on heat loss?
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The air gap is too small to allow the air to
circulate.This prevents heat loss by
convection The trapped air is a very poor
conductor which reduces heat loss through the
window.
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How does a quilt stop you getting cold at night?
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Air is trapped between the layers of material.
This cuts down on heat loss through conduction
through solids
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How does heat get transferred through space?
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Radiation
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What direction does radiation travel in?
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In straight lines
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Which of the three covered flasks of hot water
will cool down quickest? Why?
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The black one, because black is the best radiator
of heat.
Shiny Silver
Fur
Dull Black
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Two test tubes have 10ml of water and the same
starting temperature. Which test tube will show
the greatest temperature increase
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The dull, dark surface heats up quicker, it is a
good absorber of heat The shiny silver surface
heats up slowly, it is a poor absorber of heat
Light Bulb
Silver coating
Black coating
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Two test tubes are filled with 10ml of boiling
water. Which test tube will show the greatest
temperature decrease
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The dull, dark surface cools down quicker, it is
a good radiator of heat The light, shiny
surface cools down slowly, it is a poor radiator
of heat
Silver coating
Black coating
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What type of heat transfer do these images show?
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Infra-red radiation
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What type of heat transfer is an electromagnetic
wave?
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Infra - red
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When are hot objects losing heat energy?
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All the time!
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How can we cut down on heat loss in the home?
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Loft insulation Cavity Wall insulation Double
glazing Draught excluders Shut curtains
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Why is polystyrene a good heat insulator?
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Air is trapped in the bubbles of plastic. This
cuts down on heat loss through conduction through
solids