| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.85 |
| Score | 0% | 77% |
Which of these materials is not a good conductor of electricity?
tin |
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gold |
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copper |
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air |
All conductors have resistance and the amount of resistance varies with the element. In general, metals make the best conductors of electricity and non-metals make the worst conductors of electricity.
Which of the following can conduct electricity under some conditions but not others?
insulator |
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semiconductor |
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conductor |
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resistor |
Semiconductors have valence shells that are exacly half full and can conduct electricity under some conditions but not others. This property makes them useful for the control of electrical current.
The formula specifying Ohm's law is which of the following?
V = I2R |
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V = IR |
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\(V = {I \over R}\) |
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\(V = {R \over I}\) |
Ohm's law specifies the relationship between voltage (V), current (I), and resistance (R) in an electrical circuit: V = IR.
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.
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.