Devices & SystemsConvert Energy with Varying

Efficiencies

In which circuit will the bulbs not light up when the switches are closed?

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

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.

We use A LOT of energy in a day!

Chemical Electrical Mechanical Thermal

They can be converted into other forms of energy, and we can calculate the efficiencies of devices and systems.

4 Common Forms of Energy

Scientific definition is the ability to do work.

Energy

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.

To mow the lawn…

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

Unit of Energy: Joule

J

Symbol for Joule

Mr. Edwards

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).

Chemical Energy

Through chemical reactions: produce thermal energy to keep you warm, and mechanical energy so that you can move.

How do cells use glucose?

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.

Chemical energy can be transformed into other forms of energy:

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).

Thermocouple:

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..