ELECTRICAL SAFETY IN THE HOME

GFCIs (Ground Fault Circuit Interrupters) Protects people from electrical

shock by opening circuit when more current is flowing out of red terminal than into black terminal

Surge Protectors

Protects devices from momentary surges of high current by diverting the extra electricity into the ground (through the third prong)

Fuses Protect devices from electrical

meltdown due to a current that is too high

Connected in series with the circuit’s load(s)

If current gets too high thin metal filament burns out, opening circuit and stopping flow

Circuit Breakers Protect devices from electrical

meltdown due to a current that is too high

If current gets too electromagnet pulls on metal switch to open circuit and stop flow

Generating Station to Home

Brainstorm How can we reduce the amount of

electrical energy that we use?

Traditional “Electrical” Heat

Calculating Power Power is measured in units of Watts

(W) Power = Voltage x Current P = V x I

Ex. A small colour TV is connected to a 120V outlet and draws 1400 mA of current. Calculate its power rating:

Electrical Energy

Energy is measured in units of Watt-hours (W-h)

Energy = Power x Time E = P x t

Ex. How much energy does a 60 W bulb use if it is left on for one whole day?

Cost of Electricity

The rates we pay for electrical energy are quoted in dollars per kiloWatt-hour

Your total cost for electricity is found by:

Cost = Rate x Energy

Ex. How much does it cost to operate a 0.12 kW fridge for one year if energy costs $0.08 per kWh?

History of Batteries The first battery was created by

Alessandro Volta He used two different metals

separated by a salt or acid to create a potential difference

What’s Happening

In the periodic table there are many different types of metals

Metals can either gain or lose electrons

What Happens? A battery uses two different types of

metals and the one metal steals the electrons from the other metal

A Typical “Wet Cell”

Types of Batteries

There are two types of cells Dry Cell – it doesn’t use a liquid to

conduct the electrons but a paste Wet Cell – uses a liquid to conduct the

electrons

Other terminology Primary Cells – non-rechargeable cells Secondary Cells – rechargeable cells

Different Chemical Reactions Different batteries use different

metals to produce stronger or weaker potential differences (i.e. voltages) Car batteries use lead oxide and lead Alkaline Batteries use manganese

dioxide, carbon and zinc