Convert Energy with Varying Efficiencies Devices & Systems Convert Energy with Varying Efficiencies

Page 316, 7a In which circuit will the bulbs not light up when the switches are closed?

Cells are connected positive to positive- not positive to negative- no potential difference.

We use A LOT of energy in a day! 2800 hours of strenuous manual labour to produce as much energy as a typical Canadian uses daily. Team of 350 people working for 8 hours straight to supply energy for just one person.

4 Common Forms of Energy Chemical Electrical Mechanical Thermal They can be converted into other forms of energy, and we can calculate the efficiencies of devices and systems.

Energy Scientific definition is the ability to do work.

To mow the lawn… Electrical energy to spin the cutting blade. Several kinds of energy are being used: Electrical energy to spin the cutting blade. Chemical energy in the woman’s muscles is being converted into the motion or mechanical energy to move it across the lawn. Chemical energy is also converted into thermal energy as her muscles strain to push the lawnmower.

Unit of Energy: Joule James Joule: Contributed to understanding of energy; proved mechanical work & electricity can produce heat, and vice versa.

Symbol for Joule J

Mr. Edwards

Chemical Energy Is the energy found in chemicals, including food. A common molecule used for the production of energy in humans is glucose (a type of sugar).

How do cells use glucose? Through chemical reactions: produce thermal energy to keep you warm, and mechanical energy so that you can move.

Chemical Energy can be transformed into other forms of energy: Chemical energy in dynamite is rapidly released to produce the mechanical energy that demolishes buildings.

Chemical energy can be transformed into other forms of energy: A dry cell contains chemicals that react to produce electrical energy. A CD player transforms this electrical energy into mechanical energy and sound energy.

Thermocouple: Device that can convert thermal energy into electrical energy. Scientists are researching ways to use the ocean’s thermal differences to generate electricity(difference between warm surface & cold depths).

In a thermocouple, two different metals are joined together that conduct electricity at different rates. When heated, the difference in conductivity results in electricity flowing from one metal to another. Temperature affects the amount of electricity produces, so you can use a thermocouple as a thermometer..