| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.45 |
| Score | 0% | 69% |
Which of the following is not a purpose of a resistor in an electrical circuit?
limit the current in the circuit |
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control the voltage in the circuit |
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moderate the heat in the circuit |
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multiply the current in the circuit |
Resistors can be chosen in a wide variety of values to control the voltage in a circuit, limit the current, or moderate the heat produced by the components in the circuit.
A capacitor is often used for which of the following purposes?
as a primary power source |
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to maintain power in a circuit when the primary power source is disconnected |
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to allow a small amount of current to control a large amount of current |
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to convert alternating current into direct current |
Capacitors store electricity and are used in circuits as temporary batteries. Capacitors are charged by DC current (AC current passes through a capacitor) and that stored charge can later be dissipated into the circuit as needed. Capacitors are often used to maintain power within a system when it is disconnected from its primary power source or to smooth out or filter voltage within a circuit.
Alternating current changes __________ many times each second.
resistance |
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direction |
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frequency |
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period |
In contrast to the constant one-way flow of direct current, alternating current changes direction many times each second. Electricity is delivered from power stations to customers as AC because it provides a more efficient way to transport electricity over long distances.
Why does current in an electric circuit create heat?
the wire in the circuit burns when current passes through |
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voltage is naturally hot |
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current is naturally hot |
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heat is created when the current overcomes resistance in the wire |
Current in an electric circuit creates heat when the current overcomes resistance in the wire.
The voltage output of a transformer primarily depends on which of the following?
the number of turns in the wire of the coils |
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the diameter of the wire in the coils |
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the diameter of the coils |
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the conductor used for the wire in the coils |
A transformer utilizes an inductor to increase or decrease the voltage in a circuit. AC flowing in a coil wrapped around an iron core magnetizes the core causing it to produce a magnetic field. This magnetic field generates a voltage in a nearby coil of wire and, depending on the number of turns in the wire of the primary (source) and secondary coils and their proximity, voltage is induced in the secondary coil.