| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.44 |
| Score | 0% | 69% |
Which of the following is a difference between a circuit breaker and a fuse?
a fuse is cheaper than a circuit breaker |
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all of these |
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a circuit breaker can be reused |
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a fuse responds more quickly than a circuit breaker |
Like fuses, circuit breakers stop current flow once it reaches a certain amount. They have the advantage of being reusable (fuses must be replaced when "blown") but respond more slowly to current surges and are more expensive than fuses.
In metals, increasing the temperature typically _____________ conductivity.
increases |
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decreases |
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eliminates |
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does nothing to |
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.
Resistance and current are __________ proportional.
directly |
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exponentially |
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not |
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inversely |
Resistance is opposition to the flow of current and is measured in ohms (Ω). One ohm is defined as the amount of resistance that will allow one ampere of current to flow if one volt of voltage is applied. As resistance increases, current decreases as resistance and current are inversely proportional.
| 120 Ω | |
| 62 Ω | |
| 60 Ω | |
| 20 Ω |
Ohm's law specifies the relationship between voltage (V), current (I), and resistance (R) in an electrical circuit: V = IR.
Solved for resistance, R = \( \frac{V}{I} \) = \( \frac{270}{4.5} \) = 60 Ω
You would measure the amount of current through a circuit with a(n):
voltmeter |
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potentiometer |
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battery |
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ammeter |
Current is the rate of flow of electrons per unit time and is measured in amperes (A). An ammeter is used to measure the electric current in a circuit.