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