Heat

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A dull black surface will radiate and absorb heat better than a bright shiny surface.

Slide 12

Four containers were filled with warm water. Which container would have the warmest water after ten minutes?

The container would be the warmest after ten minutes because its shiny surface reflects heat _ back into the container so less is lost. The container would be the coolest because it is the best at _ heat radiation.

shiny metal

radiation

dull black

emitting

Slide 13

Radiation – Think Pair-Share

Radiation travels in straight lines

True/False

Radiation can travel through a vacuum

True/False

Radiation requires particles to travel

True/False

Radiation travels at the speed of light

True/False

Slide 14

Radiation questions

Why are houses painted white in hot countries?

White reflects heat radiation and keeps the house cooler.

Why are shiny foil blankets wrapped around marathon runners at the end of a race?

The shiny metal reflects the heat radiation from the runner back in, this stops the runner getting cold.

Slide 15

Conduction

Transfer of heat is through a SOLID by being passed from one particle to the next

Particles at the warm end move faster and this then causes the next particles to move faster and so on. e.g: poker in fire

spoon in tea

In this way heat in an object travels from: the HOT end the cold end

Slide 16

Conduction

When you heat a metal strip at one end, the heat travels to the other end.

As you heat the metal, the particles vibrate, these vibrations make the adjacent particles vibrate, and so on and so on, the vibrations are passed along the metal and so is the heat. We call this? Conduction

Slide 17

Conductors/Insulators

If a substance easily allows heat to move through it, we can say it is a good conductor of heat. e.g: most metals

If a substance does not allow heat to pass through it easily we can say it is an Insulator. E.g: wood, plastic, glass

Why do many sauce pans have plastic handles?

Slide 18

Conduction V Insulation

Slide 19

Conductor or Insulator?

Wood?

Aluminium?

Plastic?

Glass?

Iron?

Polystyrene?

Copper?

Cardboard?