Energy Transfer

Energy Transfer

Objective 1

• Objective 1: Conduction, Convection and Radiation

• You need to know these 3 vocabulary words. I will explain them in the next few slides.

Conduction

• Conduction is when heat is transferred between two objects that are touching each other.

• Think about how WE are conductors of heat. When we touch someone's hand we might transfer some of our heat to them.

• You will see conduction in the real world when:

• Cooking by conduction: The burner on the stove will conduct heat energy to the bottom of a pan on top of it.

• OR The heat from the handle of the pan is transferred to your hand when you touch it.

Here is a picture of conduction in the kitchen.

Convection

• The transfer of thermal (heat) energy by the circulation (the arrows) or movement of a liquid or gas: convection currents Hot liquid/air rises then cools as it falls.

• Just like we talked about how inside of the Earth there are convection currents that move the hot and cold air.

• Anytime you see arrows going in a circular motion this is going to be convection.

Radiation

• When heat is transferred between two objects that are not touching, and can be far apart. Heat transfer by electromagnetic waves.

• Remember: this time the objects are not touching and can be very far apart.

• It is also invisible: So for an example if you are sitting next to a fire you can not see the transfer of heat but you can feel it.

• Things in the world that use radiation to heat are:

• The sun, microwaves, television, burners, bonfire, medical imaging, stereos, ovens, phones.

Multiple Choice

Land heats up during the day by absorbing energy from the sun. The land heats up the air and then the warm air begins to rise and is now currents of cooler air. What type of heat transfer is this? Hint: this is all a circle.

• Radiation

• Conduction

• Convection

Multiple Choice

If you are heating something on the stove and the metal handle becomes hot over time what type of energy transfer causes the handle to be hot.

• Convection

• Conduction

• Radiation

Multiple Choice

If you are holding a candle and it is lit you can feel the heat. The heat travel's to your hands by -

• Radiation

• Conduction

• Convection

Objective 2

• Patterns of thermal energy

• Remember: heat always moves from a warmer to a colder place.

Scenarios

• Objective 2 is about the patterns that thermal energy follow.

• Below are some scenarios, you need to tell what will happen.

Multiple Choice

What would happen if you left a metal spoon in a cup of hot tea?

• the heat from the tea would travel to the spoon until the spoon is the same temperature as the tea

• nothing will happen

• the cold from the metal spoon will travel to the hot tea.

Multiple Choice

Which is an example of thermal conduction?

• the water in the pot absorbs heat

• the pot gets hot from the contact of the stove

• you can feel the heat from the burner.

• water boils because of the currents.

Multiple Choice

Objects that allow heat to transfer easily are known as -

• conductors

• insulators

• radiators

• energy savors

Multiple Choice

If you don't add heat what will happen to an object?

• It will stay hot.

• It will become solid

• it will cool down to room temperature

• it will melt.

Multiple Choice

Heat always goes from -

• Higher to lower temperatures

• Lower to higher temperatures

• it doesn't go anywhere