1. Science 7 – Unit C: Heat and Temperature Topic 6: Transferring Energy

2. I. Radiation Radiation is a method of transferring (moving) energy without the movement of particles. Radiation is a method of transferring (moving) energy without the movement of particles. Radiant energy travels in waves. Radiant energy travels in waves. Examples of radiant energy are: light, UV rays, radio/TV waves, and X-rays. Examples of radiant energy are: light, UV rays, radio/TV waves, and X-rays. All forms of radiant energy are called Electromagnetic Radiation (EMR). All forms of radiant energy are called Electromagnetic Radiation (EMR).

3. Infrared Radiation The form of EMR that transfers thermal energy is known as infrared radiation (IR). The form of EMR that transfers thermal energy is known as infrared radiation (IR). Like all forms of EMR, I.R. travels at the speed of light (300 million metres per second). Nothing in the universe can travel faster. Like all forms of EMR, I.R. travels at the speed of light (300 million metres per second). Nothing in the universe can travel faster. Any object warmer than absolute zero will give off I.R. Any object warmer than absolute zero will give off I.R.

4. Properties of I.R. Travels in waves in straight lines. Travels in waves in straight lines. Can travel through space Can travel through space Can be absorbed, reflected, and transmitted just like light waves. Can be absorbed, reflected, and transmitted just like light waves. Dull/dark objects absorb I.R. more than they reflect them and, Dull/dark objects absorb I.R. more than they reflect them and, Lighter/shinier objects reflect I.R. more than they absorb them. Lighter/shinier objects reflect I.R. more than they absorb them.

5. Examples of Radiation Heat lamps in fast food restaurants and incubators. Heat lamps in fast food restaurants and incubators. The Sun and stars The Sun and stars Infrared goggles Infrared goggles Fires/flames. Fires/flames.

6. II. Conduction Conduction is a method of transferring thermal energy through direct collisions between particles. Conduction is a method of transferring thermal energy through direct collisions between particles. Conduction works best with solids because the particles are basically side-by-side with each other. Conduction works best with solids because the particles are basically side-by-side with each other. Conduction is especially good with metals because the particles can conduct thermal energy so much faster than insulators like glass, or wood. Conduction is especially good with metals because the particles can conduct thermal energy so much faster than insulators like glass, or wood.

7. How Conduction Works 1. A heat source is placed beside or near a solid. 1. A heat source is placed beside or near a solid. 2. The particles on the surface nearest to the heat source absorb the energy and begin vibrating faster. 2. The particles on the surface nearest to the heat source absorb the energy and begin vibrating faster. 3. As they vibrate faster, they collide with the particles beside them faster and they begin to vibrate faster too, and they pass this energy on to the other particles until all of the particles are vibrating with the same speed. 3. As they vibrate faster, they collide with the particles beside them faster and they begin to vibrate faster too, and they pass this energy on to the other particles until all of the particles are vibrating with the same speed.

8. Applications of Conduction What are some applications of conduction? What are some applications of conduction? 1. Cooking with metal pots and pans. 1. Cooking with metal pots and pans. 2. Toaster elements cooking the toast. 2. Toaster elements cooking the toast. 3. Thermal blankets. 3. Thermal blankets.

9. III. Convection Convection is a method of transferring energy in fluids in a circular motion. Convection is a method of transferring energy in fluids in a circular motion. In convection, the warmer particles in a fluid (gas or liquid) move away from the heat as they have more energy. In convection, the warmer particles in a fluid (gas or liquid) move away from the heat as they have more energy. This movement forces the colder particles out of the way and some of them are pushed near the heat source. This movement forces the colder particles out of the way and some of them are pushed near the heat source.

10. How Convection Works Cont’d The colder particles are heated and move themselves. The colder particles are heated and move themselves. As the warmer particles move away from the heat source they lose energy, and move back down to the heat source. As the warmer particles move away from the heat source they lose energy, and move back down to the heat source. This whole cycle repeats itself and forms a circular motion where the warmer particles move away from the heat source, and cooler particles move back towards the heat source. This whole cycle repeats itself and forms a circular motion where the warmer particles move away from the heat source, and cooler particles move back towards the heat source.

11. Applications of Convection 1. Ovens which use the heating of air particles to uniformly cook food. 1. Ovens which use the heating of air particles to uniformly cook food. 2. Furnace heating of homes. 2. Furnace heating of homes. 3. Radiator heating of liquids. 3. Radiator heating of liquids.

12. What is an Energy Transfer System? Energy Transfer System – is a process where energy is moved from place to place or changed from one form to another. Energy Transfer System – is a process where energy is moved from place to place or changed from one form to another. Any energy transfer system has the following five things in common: Any energy transfer system has the following five things in common:

13. 1. Energy Source This is where the energy originates. This is where the energy originates. The energy source can be mechanical, chemical, radiant, nuclear, or electrical. The energy source can be mechanical, chemical, radiant, nuclear, or electrical. Examples include nuclear power plants, batteries, or a fire-pit. Examples include nuclear power plants, batteries, or a fire-pit.

14. 2. Direction of Energy Transfer Energy is always transferred from an area of more energy (energy source) to an area of lower energy. Energy is always transferred from an area of more energy (energy source) to an area of lower energy. Most of this energy is transferred evenly through the environment. Most of this energy is transferred evenly through the environment. Example: the energy in a fire is spread throughout the air. In a battery or power plant, the energy flows away in circuits. Example: the energy in a fire is spread throughout the air. In a battery or power plant, the energy flows away in circuits.

15. 3. Transformations Energy can also change its form when it is transferred. Energy can also change its form when it is transferred. For example, a battery takes chemical energy and makes it into electrical energy. For example, a battery takes chemical energy and makes it into electrical energy. Gasoline in an engine takes chemical energy and changes it into mechanical energy. Gasoline in an engine takes chemical energy and changes it into mechanical energy.

16. 4. Waste Heat Anytime energy is transferred or transformed some of the energy is lost to the surroundings, usually as wasted heat. Anytime energy is transferred or transformed some of the energy is lost to the surroundings, usually as wasted heat. Example, a light bulb changes electrical energy to light energy, however 90% of its energy is wasted as heat. Example, a light bulb changes electrical energy to light energy, however 90% of its energy is wasted as heat.

17. 5. Control System A device that can start and stop the transfer of energy and/or control the amount of energy being transferred. A device that can start and stop the transfer of energy and/or control the amount of energy being transferred. Examples include power switches, thermostats, dimmer switches, volume controls, etc. Examples include power switches, thermostats, dimmer switches, volume controls, etc.