Understanding Heat Transfer, Conduction, Convection and Radiation Notes
•Heat always moves from a ______place to a ______place.
•Hot objects in a cooler room will ______to room temperature.
•Cold objects in a warmer room will ______to room temperature.
•Heat transfers in three ways:
•______
•______
•______
Conduction
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? ______
The outer e______of metal atoms drift, and are free to move. When the metal is heated, this ‘sea of electrons’ gain k______energy and transfer it throughout the metal. Insulators, such as w______and p______, do not have this ‘sea of electrons’ which is why they do not conduct heat as well as metals.
Convection
Air and Water Movement
What happens to the particles in a liquid or a gas when you heat them?
The particles ______out and become ______dense.
Cooler, more d______, fluids sink through w______, less dense fluids.
In effect, warmer liquids and gases r______up. Cooler liquids and gases s______.
Convection currents are formed as water warms; warm water rises and cool water sinks. Air works the same way; the cold air form the sea moves in to take the warm air that has risen.
Where is the freezer compartment put in a fridge? It is put at the ______, because cool air ______, so it cools the food on the way down. It is ______at the bottom, so this warmer air ______and convection current is set up.
Radiation
How does heat energy get from the Sun to the Earth?
There are ______between the Sun and the Earth so it CANNOT travel by ______or by ______.
Radiation is energy leaving in the form of an electromagnetic ______(such as light). Radiation is the ______form, but it is impossible to stop. Radiation travels in ______and can travel through a ______(for example, air).
Emitting (Releasing) Heat
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.
Absorbing Heat
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.
Questions
Why does hot air rise and cold air sink?
Why are boilers placed beneath hot water tanks in people’s homes?
Why are houses painted white in hot countries?
Why are shiny foil blankets wrapped around marathon runners at the end of a race?
In which of the following are the particles closest together?
How does heat energy reach the Earth from the Sun?
Which is the best surface for reflecting heat radiation?
Which is the best surface for absorbing heat radiation?