| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.42 |
| Score | 0% | 68% |
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 the formula for calculating electrical power?
\(P = {I \over V}\) |
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P = IV |
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\(P = {V \over I}\) |
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P = I2V |
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.
Longer the electrical wires mean _______________ voltage drop.
complete |
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lesser |
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greater |
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diminishing |
Electrical wires have a certain amount of resistance per foot. A longer wire means more resistance and a greater voltage drop.
Which of the following is not an advantage of semiconductors over conductors?
a semiconductor conducts current better than a conductor |
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a semiconductor exhibits increased conductivity with increased temperatures |
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materials to produce semiconductors are cheap and abundant |
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a semiconductor's conductivity can be varied under an external electrical field |
A semiconductor is a material that has a limited ability to conduct electrical current with conductivity between that of an insulator and that of a conductor. Silicon, a cheap and abundant material, is the most used semiconductor material although other materials are used in the electronics components made from semiconductors. The primary advantages of a semiconductor over a conductor is that the conductivity of a semiconductor can be varied under an external electrical field giving engineers precise control over complex circuits and, unlike conductors like metals, a semiconductor's conductivity increases with increased temperatures.