| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.59 |
| Score | 0% | 72% |
The formula specifying Ohm's law is which of the following?
\(V = {I \over R}\) |
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\(V = {R \over I}\) |
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V = I2R |
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V = IR |
Ohm's law specifies the relationship between voltage (V), current (I), and resistance (R) in an electrical circuit: V = IR.
In an electrical circuit, resistors have fixed or __________ resistance.
variable |
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parallel |
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series |
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dynamic |
Resistors are used to limit voltage and/or current in a circuit and can have a fixed or variable resistance. Variable resistors (often called potentiometers or rheostats) are used when dynamic control over the voltage/current in a circuit is needed, for example, in a light dimmer or volume control.
What is the frequency of most household electrical systems?
110Hz |
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60Hz |
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110V |
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60MHz |
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 maintain power in a circuit when the primary power source is disconnected |
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as a primary power source |
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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.
| 360 W | |
| 108 W | |
| 120 W | |
| 129 W |