| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.38 |
| Score | 0% | 68% |
Which of the following is not a characteristic of a step-up transformer?
has more turns in the secondary winding than in the primary winding |
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the secondary voltage is higher than the primary voltage |
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the primary voltage is higher than the secondary voltage |
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increases voltage |
As their names indicate, a step-up transformer is used to step up or increase voltage and a step-down transformer is used to step down or decrease voltage. In a step-up transformer, the secondary voltage is higher than the primary voltage and it has more turns in the secondary winding than in the primary winding.
Which of the following will increase the magnetic field produced by the electric current in a wire?
construct the wire from conductive material |
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wind the wire into a coil |
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construct the wire from insulative material |
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wrap the wire around a ceramic core |
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.
The formula specifying Ohm's law is which of the following?
\(V = {I \over R}\) |
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V = IR |
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V = I2R |
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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 is a difference between a circuit breaker and a fuse?
a fuse responds more quickly than a circuit breaker |
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a circuit breaker can be reused |
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a fuse is cheaper than a circuit breaker |
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all of these |
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.
This circuit component symbol represents a(n):
transformer |
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inductor |
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capacitor |
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resistor |
An inductor is coiled wire that stores electric energy in the form of magnetic energy and resists changes in the electric current flowing through it. If current is increasing, the inductor produces a voltage that slows the increase and, if current is decreasing, the magnetic energy in the coil opposes the decrease to keep the current flowing longer. In contrast to capacitors, inductors allow DC to pass easily but resist the flow of AC.