| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.08 |
| Score | 0% | 62% |
Which of the following is not a characteristic of direct current?
an example power source is a generator |
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used to power your cell phone |
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electrons flow in only one consistent direction |
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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.
The joule is a unit of measurement for:
power |
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capacitance |
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resistance |
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energy |
The joule is a unit of measurement for energy.
In an electronic circuit, a thermocouple can be used to:
open or close a circuit at a designated temperature |
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keep the circuit at a designated safe temperature |
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increase or decrease the temperature of a component in the circuit |
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link the temperature of one component in the circuit to that of another component in the circuit |
A thermocouple is a temperature sensor that consists of two wires made from different conductors. The junction of these two wires produces a voltage based on the temperature difference between them and can be used like a switch to open or close the circuit at a designated temperature.
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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copper is durable and relatively cheap |
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silver and gold are brittle |
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all of these |
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.
This circuit diagram represents a(n):
parallel circuit |
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open circuit |
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series-parallel circuit |
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series circuit |
A series circuit has only one path for current to flow. In a series circuit, current (I) is the same throughout the circuit and is equal to the total voltage (V) applied to the circuit divided by the total resistance (R) of the loads in the circuit. The sum of the voltage drops across each resistor in the circuit will equal the total voltage applied to the circuit.