Chapter 11Using Electricity

11.1 - Work, Energy and PowerWork - transforming or converting of energy

Energy

An object has energy (E) it has the ability to do work

Two main types:

Energy that is stored

Potential Energy (PE)

Kinetic Energy (KE)

Energy of an object in motion

Work = Change in Energy

Law of Conservation of Energy

In any closed system, the total amount of energy remains constant

When all types of energy are added up, the total NEVER changes, no matter what!

Power

Power is the rate at which energy is transformed (or rate at which work is being done)

Measured in watts (W). 1 W = 1 J/s

remember that so …..

Homework: Read 11.1 in your textbook and do the following questions pg. 339 - # 4 - 9

11.2 - Electrical Energy and Power

Electrical Energy, Time, and Power

Homework: Read 11.2 in your textbook and do the following questions pg. 344 - # 2 - 7, 9 - 11

11.4 - Household Electrical Energy

The History of the Electrical Power Industry

Before electricity:

Lamps fuelled by natural gas and oils

Gaslights used to light streets

First lightbulb:

1879 - Edison

First power plant:

1882 - New York100 V; DC - needed large currents, gave low power

AC electricity

Tesla/Westinghouse - allowed transmission of higher power electricity

The Electric Meter

We know that: ΔE = P x (Δt)

Usually, E is in Joules (J).For measuring electricity usage, it is kWh (kilowatt hour)

Number of Joules is too large, so kWh is used.

EnerGuide Labels

Gives information on how much energy is used

Compares it to other models of the same kind

Homework: Read 11.4 in your textbook and do the following questions pg. 354 - # 1 - 12