| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 2.80 |
| Score | 0% | 56% |
Which of the following is not an advantage of semiconductors over conductors?
a semiconductor's conductivity can be varied under an external electrical field |
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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 |
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.
In metals, increasing the temperature typically _____________ conductivity.
eliminates |
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decreases |
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does nothing to |
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increases |
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.
Which of the following is not a characteristic of direct current?
electrons flow in only one consistent direction |
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used to power your cell phone |
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an example power source is a generator |
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cannot easily travel distances without power loss |
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.
From what energy do photovoltaic cells produce electrical energy?
sun |
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chemical |
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nuclear |
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magnetic |
A photovoltaic cell (also known as a solar cell) converts energy from the sun into electrical energy.
| parallel | |
| series | |
| series-parallel | |
| orthogonal |
Connecting the 8 batteries in series multiplies their voltage while keeping their current the same yielding a 48V 10A configuration. Connecting the 8 batteries in parallel multiplies their current while keeping their voltage the same yieleding a 6V 80A configuration. Using a series-parallel connection, 4 batteries can be connected in series and 4 can be connected in parallel resulting in a 24V 40A configuration.