| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 2.64 |
| Score | 0% | 53% |
Which of the following is not a characteristic of direct current?
an example power source is a generator |
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electrons flow in only one consistent direction |
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used to power your cell phone |
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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.
Which of the following is not an advantage of semiconductors over conductors?
a semiconductor conducts current better than a conductor |
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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 |
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a semiconductor exhibits increased conductivity with increased temperatures |
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.
What is the potential difference in an electrical circuit a measure of?
the resistance at a specific location in the circuit |
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the current at a specific location in the circuit |
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the voltage at a specific location in the circuit |
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the load at a specific location in the circuit |
Electrons flow from an area of high concentration to an area of low concentration. A high voltage indicates a high concentration of electrons that creates a greater potential for electron flow than a low voltage. When applied to a load, voltage creates electricity and potential difference is the measure of voltage at a specific location in an electrical circuit.
Which of the following is a characteristic of batteries connected in parallel?
one connection is made between each adjacent battery |
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total current equals the sum of the individual battery currents |
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the positive terminal of one battery is connected to the negative terminal of the next |
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total current equals the average of the individual battery currents |
You can multiply the voltage or the current supplied by individual batteries by connecting them together either in series or in parallel. The characteristics of batteries connected in parallel are that total voltage equals the average of the individual battery voltages, total current equals the sum of the individual battery currents, the positive terminal of one battery is connected to the positive terminal of the next, the negative terminal of one battery is connected to the negative terminal of the next, and two connections are made between each adjacent battery.
The voltage output of a transformer primarily depends on which of the following?
the diameter of the coils |
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the diameter of the wire in the coils |
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the conductor used for the wire in the coils |
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the number of turns in the wire of the coils |
A transformer utilizes an inductor to increase or decrease the voltage in a circuit. AC flowing in a coil wrapped around an iron core magnetizes the core causing it to produce a magnetic field. This magnetic field generates a voltage in a nearby coil of wire and, depending on the number of turns in the wire of the primary (source) and secondary coils and their proximity, voltage is induced in the secondary coil.