| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.77 |
| Score | 0% | 75% |
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.
| 202 W | |
| 600 W | |
| 203 W | |
| 200 W |
The joule is a unit of measurement for:
capacitance |
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resistance |
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power |
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energy |
The joule is a unit of measurement for energy.
Alternating current changes __________ many times each second.
frequency |
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period |
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direction |
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resistance |
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.
From what energy do photovoltaic cells produce electrical energy?
magnetic |
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sun |
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nuclear |
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chemical |
A photovoltaic cell (also known as a solar cell) converts energy from the sun into electrical energy.