11.1 CELLS AND BATTERIES

How must the components in a flashlight be connected in order for the

flashlight to function?

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What can cause a flashlight to stop functioning?

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Electric circuits:

- pathways that electrons can flow

- electrons are powered by an energy source

- Contains a source, conductor, a load, and a control

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Cells Batteries

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a cell or a battery:

- The source of electrical energy in a circuit

A battery is two or more cells connected together.

Voltaic cells

- generates an electric current by chemical reactions

- involve two different metals and a conducting solution.

The first voltaic cells

- constructed around 1800 by Alessando Volta

- stacked alternating discs made of silver and zinc

- separated by pieces of cloth soaked in salt water.

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Electrodes:

- either of the two metal terminals found in a cell

or battery

Electrolyte:

- the solution or paste that conducts charge between

the two electrodes.

Electrons or ions move in all types of cells.

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Types of Cells

Dry cells: cells with an electrolyte that is a paste.

Wet cells: cells with a liquid electrolyte (eg. sulphuric acid)

Dry Cells Wet Cells

Types of Cells

Primary cells: can be used only once

Secondary cells: can be recharged

Secondary Cells

During recharging, the chemical reaction in the cell is reversed.

Primary Cells

Copyright © 2010 McGraw-Hill Ryerson Ltd.

Cells and Batteries in Common Use (Page 441)

The first electric cars: built more than a century ago.

Today’s vehicles: mostly powered by gasoline or diesel (fossil fuels)

Disadvantages: 1) increasing fuel costs

2) concern for the environment

Electric vehicles: powered only by batteries

Hybrids: a combination of batteries and a fossil fuel engine

A fuel cell

- generates electricity through the chemical reactions

- fuel is stored outside the cells cell can be refuelled as needed

- originally developed for the U.S. space program

- can be used to provide energy for automobiles, buses, homes, and

even small devices like cell phones

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Solar cells

- convert sunlight into electrical energy

- sunlight strikes a semiconductor (eg. Silicon)

electrons are knocked loose from the atoms

- can be used to power anything from calculators and ornamental lights to

homes, satellites, and even communities

Images courtesy of SkyPower.

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In October of 2009, First Light 1, a 9.1 megawatt solar park, opened in

Stone Mills, Ontario.

The first and largest solar energy farm in Canada covers an area the size of

50 football fields.

Images courtesy of SkyPower.