| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.30 |
| Score | 0% | 66% |
The rate of flow of electrons per unit time is which of the following?
current |
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voltage |
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resistance |
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conductance |
Current is the rate of flow of electrons per unit time and is measured in amperes (A). A coulomb (C) is the quantity of electricity conveyed in one second by a current of one ampere.
Which of the following is not a characteristic of direct current?
electrons flow in only one consistent direction |
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cannot easily travel distances without power loss |
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an example power source is a generator |
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used to power your cell phone |
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 DC is a battery. 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.
In metals, increasing the temperature typically _____________ conductivity.
does nothing to |
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increases |
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eliminates |
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decreases |
All conductors have resistance and the amount of resistance varies with the element. Metals exhibit increased resistance (and, therefore, lower conductivity) as their temperature increases.
Why does current in an electric circuit create heat?
voltage is naturally hot |
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the wire in the circuit burns when current passes through |
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heat is created when the current overcomes resistance in the wire |
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current is naturally hot |
Current in an electric circuit creates heat when the current overcomes resistance in the wire.
| 14 A | |
| 9 A | |
| 10.5 A | |
| 7 A |
Ohm's law specifies the relationship between voltage (V), current (I), and resistance (R) in an electrical circuit: V = IR.
Solved for current, I = \( \frac{V}{R} \) = \( \frac{70}{10} \) = 7 A