| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.55 |
| Score | 0% | 71% |
Which of the following statements about electrical resistance is true?
the less resistive the conductor is the slower electron flow will be |
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the more resistive the conductor is the slower electron flow will be |
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the more resistive the conductor is the faster electron flow will be |
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electrically conductive materials have no resistive properties |
Resistance is opposition to the flow of current. As resistance increases, current decreases as resistance and current are inversely proportional.
Why is an insulator a poor conductor of electricity?
an insulator has many free electrons |
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an insulator has few free electrons |
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an insulator is made of organic material |
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an insulator is made of inorganic material |
Insulators have valence shells that are more than half full of electrons and, as such, are tightly bound to the nucleus and difficult to move from one atom to another.
The watt is a unit of measurement for:
frequency |
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resistance |
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power |
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energy |
Electrical power is measured in watts (W) and is calculated by multiplying the voltage (V) applied to a circuit by the resulting current (I) that flows in the circuit: P = IV. In addition to measuring production capacity, power also measures the rate of energy consumption and many loads are rated for their consumption capacity. For example, a 60W lightbulb utilizes 60W of energy to produce the equivalent of 60W of heat and light energy.
Which of the following is not a characteristic of a step-up transformer?
the primary voltage is higher than the secondary voltage |
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the secondary voltage is higher than the primary voltage |
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has more turns in the secondary winding than in the primary winding |
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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.
Silver and gold are among the most highly conductive elements. Why is copper used much more often as a conductor in electrical circuits?
silver and gold are costly |
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silver and gold are brittle |
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all of these |
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copper is durable and relatively cheap |
All conductors have resistance and the amount of resistance varies with the element. But, resistance isn't the only consideration when choosing a conductor as the most highly conductive elements like silver and gold are also more expensive and more brittle than slightly less conductive elements like copper. A balance needs to be struck between the electrical qualities of a material and its cost and durability.