# Physics Unit 1 Lesson B1: Part 1 Energy Transfer

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Physics Unit 1 Lesson B1: Part 1 Energy Transfer
Learning objectives: Explain how energy is transferred by conduction, convection and radiation.

A Bunsen Burner flame is a hot object
A Bunsen Burner flame is a hot object. Where will it transfer it’s heat energy to?

A Bunsen Burner flame is a hot object
A Bunsen Burner flame is a hot object. Where will it transfer it’s heat energy to? It’s surroundings

How is the energy transferred
How is the energy transferred? Draw a diagram of a Bunsen Burner and add the following labels.

How is the energy transferred?
Hot Air (NOT HEAT) rises because it is less dense. Cold air will replace it and heat up itself. This is called convection.

How is the energy transferred?
Infrared is emitted (given off) in all directions. Cool objects will absorb this and heat up. This is called Radiation

How is the energy transferred?
Heat energy will be passed between the atoms in a solid. This is called Conduction

Copy and complete Heat energy can be transferred by ____________, _____________ or _____________. Heat energy moves from _____ objects to cooler ones, until their temperatures are ________.

Copy and complete Heat energy can be transferred by Conduction, Convection or Radiation. Heat energy moves from hot objects to cooler ones, until their temperatures are equal.

Radiation Radiation is where heat energy is transferred by infrared radiation. This thermogram shows where most infrared is been emitted (given off). The hotter an object, the more infrared it gives off. This heat feels warm. This is because you are absorbing the infrared energy and heating up.

Radiation Matt (not shiny), black objects are very good absorbers of infrared. They will absorb infrared and warm up quickly. (They do not attract it – if you write the word attract in your exam you will always get the answer wrong, the correct word is ABSORB) Matt, Black objects are also very good emitters of infrared. They will cool down quickly as they get rid of their energy quickly.

Radiation Silver (or White), Shiny objects are very poor absorbers. They reflect the infrared and don’t absorb it. This means they don’t heat up very quickly. Silver shiny objects are very bad emitters. This means they will stay hot for longer, as they lose emit their heat energy very quickly.

Try these questions. Write a detailed answer in your books. Use the ideas on emitting and absorbing infrared

What colour are solar panels? Why are they this colour?

2. Why are these houses painted white?

3. Which cars will heat up the fastest on a sunny day?
4. Which cars will cool down fastest at night?

5. In hot countries, why is it sometimes better to wear white clothes, and sometimes better to wear black clothes?

6. Why do runners cover themselves in tinfoil after a race?

7. Which kettle will stay warm for longest (in terms of radiation)

8. Assuming they are both at the same temperature, which drink will cool fastest?