| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.23 |
| Score | 0% | 65% |
Direct current flows from the __________ terminal of the voltage source to the __________ terminal.
positive, negative |
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negative, negative |
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positive, positive |
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negative, positive |
Direct current flows in only one direction in a circuit, from the negative terminal of the voltage source to the positive. A common source of direct current (DC) is a battery.
Electromotive force is another name for:
voltage |
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energy |
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current |
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power |
Voltage (V) is the electrical potential difference between two points. Electrons will flow as current from areas of high potential (concentration of electrons) to areas of low potential. Voltage and current are directly proportional in that the higher the voltage applied to a conductor the higher the current that will result.
Which of the following is not a purpose of a resistor in an electrical circuit?
limit the current in the circuit |
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control the voltage in the circuit |
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moderate the heat in the circuit |
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multiply the current in the circuit |
Resistors can be chosen in a wide variety of values to control the voltage in a circuit, limit the current, or moderate the heat produced by the components in the circuit.
Alternating current changes __________ many times each second.
frequency |
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period |
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resistance |
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direction |
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.
The valence shell of a semiconductor is how full of electrons?
less than half full |
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empty |
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more than half full |
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half full |
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.