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How does heat energy get from
the Sun to the Earth?
There are no particles
between the Sun and the
Earth so it CANNOT travel
by conduction or by
convection.
? RADIATION
Radiation:
The transfer of heat (infrared rays) by means of electromagnetic waves. This heat energy transfers though empty space or a vacuum at the speed of light. No mass is exchanged and no medium is required in the process of radiation
Examples of things that Radiate Heat: The Sun Fire Light Bulbs Heat Lamps Toaster Oven
Object that are good absorbers of radiant energy are
also good emitters of radiant energy.
Darker colored surfaces absorb energy faster than
light colored surfaces. (They both will eventually reach
the same temperature over time)
Practical Applications of Examples of Radiant Heat:
1. Outdoor Dress:
• Wear dark colored clothes in winter
• Wear light colored clothes in summer
2. Heat lamp in fast food restaurants
3. Toasting bread; Microwave cooking
4. Fireplaces; Electric space heaters
All objects emit infrared radiation. Heating an object up makes it radiate more infrared. Thermal energy from infrared waves is called radiant
heat or radiation.
Four containers were filled with warm water. Which container would have
the warmest water after ten minutes?
Shiny metal
Dull metal
Dull black
Shiny black
The __________ container would be the warmest after ten minutes
because its ____________reflects heat radiation back into the
container so less is lost. The ________ container would be the
coolest because it is the best at ___________ heat radiation.
shiny metal
shiny surface
dull black
absorbing
Four containers were placed equidistant from a heater. Which container
would have the warmest water after ten minutes?
The __________ container would be the warmest after ten minutes
because its surface absorbs heat __________ the best. The
_________ container would be the coolest because it is the poorest
at __________ heat radiation.
dull black
radiation
shiny metal
absorbing
Shiny metal
Dull metal
Dull black
Shiny black
The police and fire service use
infra-red cameras to find people in
the dark.
Infra-red has no color, but a
computer can put a false color on
the camera image so we can ‘see’
the object.
The colors are put on a scale which
corresponds to temperature.
Why does hot air rise and cold air sink?
Cool air is more dense than warm air, so
the cool air ‘falls through’ the warm air.
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.
Which of the following is not a method of
heat transfer?
A. Radiation
B. Insulation
C. Conduction
D. Convection
In which of the following are the particles
closest together?
A. Solid
B. Liquid
C. Gas
D. Fluid
How does heat energy reach the Earth
from the Sun?
A. Radiation
B. Conduction
C. Convection
D. Insulation
Which is the best surface for reflecting
heat radiation?
A. Shiny white
B. Dull white
C. Shiny black
D. Dull black
Which is the best surface for absorbing
heat radiation?
A. Shiny white
B. Dull white
C. Shiny black
D. Dull black
Heat transfer thru fluids and gases by bulk
movement of molecules
A. Radiation
B. Conduction
C. Convection
D. Insulation
Heat transfer thru solids by direct contact
A. Radiation
B. Conduction
C. Convection
D. Insulation
Conduction, Convection, and Radiation
Conduction, Convection, and Radiation
Conduction, Convection, and Radiation
Conduction, Convection, and Radiation
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