Household Circuits

The ​ (a)   you use in your home may have been ​ (b)   hundreds of miles away. Most ​ (c)   energy in North America is made from ​ (d)   . The real source of our electrical energy is the ​ (e)   .

• electricity
• generated
• electrical
• fossil fuels
• sun

Millions of years ago, ​ (a)   covered the earth and became trapped in ​ (b)   layers. The ​ (c)   swamps produce ​ (d)   , oil, and natural gas. These ​ (e)   fuels are mined from the earth’s crust.

• swamps
• rock
• decayed
• coal
• fossil

Fossil fuels can be ​ (a)   to high temperatures to create ​ (b)   . The potential ​ (c)   of the steam spins large blades in turbines to produce kinetic energy. The​ (d)   energy is used to operate a generator, which converts the kinetic energy into ​ (e)   .

• heated
• steam
• energy
• kinetic
• electricity

Generators produce an electric ​ (a)   that alternates back and forth. It is therefore called ​ (b)   current (A.C.). The current operating your household ​ (c)   is alternating with a frequency of 60 hertz (Hz). One ​ (d)   means one vibration per second.

• current
• alternating
• appliances
• hertz

Alternating current is preferred for ​ (a)   industrial and home use because with A.C. devices called​ (b)   can be used. Transformers can ‘step-up’ or ‘step-down’ ​ (c)   easily. When a transformer ‘steps-up’ (increases) voltage, it also ‘steps-down the ​ (d)  

• large-scale
• transformers
• voltage
• current.

When ​ (a)   must be transmitted over long distances, it is essential that the ​ (b)   be kept as low as possible. This reduces the ​ (c)   effect in the wires carrying the current and less electrical ​ (d)   is wasted as heat energy given off by the ​ (e)   wires.

• electricity
• current
• heating
• energy
• transmission

Electricity may be ​ (a)   over very long distances to communities. ​ (b)   as high as 500 000 volts may be used. The ​ (c)   , however, is small. When the power lines reach a community, the voltage is ​ (d)   by transformers, in stages

• transmitted
• current
• Voltages
• ‘stepped-down’

The voltage between the ​ (a)   entering the ​ (b)   out on your street may be as high as 14 400 volts. The street transformer steps the voltage ​ (c)   to 120 volts or 240 volts before it is delivered to your ​ (d)   .

• lines
• transformer
• down
• house

From your street transformer, ​ (a)   wires come into your house. These three wires pass through an ​ (b)   . The meter measures how much electrical energy you use in units called ​ (c)   . From the meter, the wires go to a service entrance ​ (d)   . This is where various circuit​ (e)   and the master switch for your house is located.

• three
• electric meter
• kilowatt hours
• panel
• breakers

Of the ​ (a)   wires that enter your house from the transformer, two are ​ (b)   , or hot and the third wire is ​ (c)   . The hot wires are colored ​ (d)   and the neutral wire is ​ (e)   . Both the hot wires are at 120 volts relative to the neutral wire. Relative to each other the two hot wires are at 240 volts.

• three
• live
• neutral
• black and red
• white