| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.10 |
| Score | 0% | 62% |
Why does current in an electric circuit create heat?
the wire in the circuit burns when current passes through |
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current is naturally hot |
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voltage 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 valence shell of a conductor is how full of electrons?
full |
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less than half full |
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half full |
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more than half full |
Conductors are elements that allow electrons to flow freely. Their valence shell is less than half full of electrons that are able to move easily from one atom to another.
A solid state device has which of the following characteristics?
made entirely from conductive material |
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made from a mix of conductive and insulative material |
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made entirely from semiconductor material |
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made entirely from insulative material |
The transistor is the foundation of modern electronic devices. It is made entirely from semiconductor material (making it a solid state device) and can serve many different functions in a circuit including acting as a switch, amplifier, or current regulator. A transistor works by allowing a small amount of current applied at the base to control general current flow from collector to emitter through the transistor.
What is the frequency of most household electrical systems?
60MHz |
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110V |
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110Hz |
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60Hz |
Electricity is delivered from power stations to customers as AC because it provides a more efficient way to transport electricity over long distances. Most households use electricity with a frequency of 60Hz.
A capacitor is often used for which of the following purposes?
to convert alternating current into direct current |
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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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as a primary power source |
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.