| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.35 |
| Score | 0% | 67% |
What is the frequency of most household electrical systems?
60MHz |
|
110Hz |
|
110V |
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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.
Which of the following allows current to pass easily in one direction and blocks current in the other direction?
diode |
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inductor |
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resistor |
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capacitor |
A diode allows current to pass easily in one direction and blocks current in the other direction. Diodes are commonly used for rectification which is the conversion of alternating current (AC) into direct current (DC). Because a diode only allows current flow in one direction, it will pass either the upper or lower half of AC waves (half-wave rectification) creating pulsating DC. Multiple diodes can be connected together to utilize both halves of the AC signal in full-wave rectification.
A transformer utilizes an inductor to increase or decrease what in a circuit?
load |
|
resistance |
|
voltage |
|
current |
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.
The conductivity of an element depends on how many electrons occupy which electron shell?
inner |
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middle |
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first |
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outer |
All electricity is the movement of electrons which are subatomic particles that orbit the nucleus of an atom. Electrons occupy various energy levels called shells and how well an element enables the flow of electrons depends on how many electrons occupy its outer (valence) electron shell.
Which of the following will increase the magnetic field produced by the electric current in a wire?
wind the wire into a coil |
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wrap the wire around a ceramic core |
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construct the wire from conductive material |
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construct the wire from insulative material |
A moving electric current produces a magnetic field proportional to the amount of current flow. This magnetic field can be made stronger by winding the wire into a coil and further enhanced if done around an iron containing (ferrous) core.