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Flashcards for reviewing concepts about electric circuits, including circuit diagrams, series and parallel circuits, power and energy calculations, and electrical safety.
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What is the purpose of wiring in a building?
Wiring installed by an electrician to bring electric current into a building, usually from one main box in a house.
What do circuit diagrams use to represent the parts of a circuit?
Symbols representing parts of a circuit, including an energy source and devices run by electrical energy.
What is an electric circuit?
A complete path through which charge can flow.
What does a circuit diagram show?
Shows one or more complete paths in which charge can flow, with arrows indicating current direction from positive to negative.
What do switches indicate in a circuit?
Shows where a circuit can be opened to stop the flow of current.
What happens when a switch is open in a circuit?
The circuit is not a complete loop, and current stops flowing.
What happens when a switch is closed in a circuit?
The circuit is complete, allowing charge to flow.
What happens if one element stops functioning in a series circuit?
If one element fails, none of the elements operate because charge has only one path.
What happens if one element stops functioning in a parallel circuit?
If one element fails, the others can still operate because charge has multiple paths.
How does charge flow in a series circuit?
Charge has only one path through which to flow.
What happens if a bulb burns out in a series circuit?
It becomes an open circuit, stopping the flow of charge.
How does adding bulbs to a series circuit affect the current and brightness?
Adding bulbs increases resistance, decreases current, and makes each bulb shine less brightly.
What is a parallel circuit?
An electric circuit with two or more paths through which charges can flow.
What happens if one bulb burns out in a parallel circuit?
Charge still flows along the other paths, and the other bulbs stay lit.
Why are electric circuits in a home wired in parallel?
So they can operate independently.
How is electric power calculated?
Voltage multiplied by current.
What is the unit of electric power?
The joule per second, or watt (W).
If an electric oven is connected to a 240-volt line and uses 34 amps of current, what is the power used by the oven?
An oven uses 8200 watts of power.
A clothes dryer uses about 27 amps of current from a 240-volt line. How much power does it use?
6500 W
A camcorder has a power rating of 2.3 watts. If the output voltage from its battery is 7.2 volts, what current does it use?
0.32 A
A power tool uses about 12 amps of current and has a power rating of 1440 watts. What voltage does the tool require?
120 V
How do you find the electrical energy used by an appliance?
Multiply power by time.
What devices help make electricity safe to use?
Correct wiring, fuses, circuit breakers, insulation, and grounded plugs.
What happens if the current in a household circuit exceeds the safety limit?
The wire may overheat if the current exceeds the circuit’s safety limit.
What does a fuse do?
Prevents current overload by melting a wire if too much current passes through it.
What is a circuit breaker?
A switch that opens when current in a circuit is too high.
Why is electrical wiring insulated?
To protect people from shocks.
Why should you avoid touching electrical devices with wet hands?
They conduct current more readily when they are wet.
What do three-prong plugs do?
Prevent shocks caused by short circuits.
What is grounding?
The transfer of excess charge through a conductor to Earth.
What does a ground-fault circuit interrupter (GFCI) do?
It monitors current flowing to and from an outlet, and opens the circuit if these currents are not equal.
A number of light bulbs are connected to an energy source in a series circuit. What will happen to the other bulbs if one of the bulbs burns out?
They will turn off.
A pair of 15-watt computer speakers are connected to a 12-volt power supply. What is the electric current running through the speakers?
1.25 A
A ground-fault circuit interrupter is a switch that opens to prevent overheating when the current in a circuit is too high. True or False?
False, it is a circuit breaker.