| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.44 |
| Score | 0% | 69% |
A capacitor is often used for which of the following purposes?
as a primary power source |
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to allow a small amount of current to control a large amount of current |
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to convert alternating current into direct current |
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to maintain power in a circuit when the primary power source is disconnected |
Capacitors store electricity and are used in circuits as temporary batteries. Capacitors are charged by DC current (AC current passes through a capacitor) and that stored charge can later be dissipated into the circuit as needed. Capacitors are often used to maintain power within a system when it is disconnected from its primary power source or to smooth out or filter voltage within a circuit.
The ampere is a unit of measurement for:
inductance |
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power |
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current |
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energy |
Current is the rate of flow of electrons per unit time and is measured in amperes (A). A coulomb (C) is the quantity of electricity conveyed in one second by a current of one ampere.
Which of the following statements about a capacitor is false?
you should always discharge any capacitors before working on an electronic circuit |
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it is safe to touch a capacitor with your hands as long as it is small |
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a capacitor remains charged even after the input voltage is removed |
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to discharge a capacitor safely, use a high-wattage resistor comparable to the capacitance of the capacitor |
The purpose of a capacitor is to retain electric charge and it will do so even after its input voltage is removed. After the input voltage is removed, the capacitor will slowly discharge but, depending on the size and characteristics of the capacitor, discharging could take from a few minutes to a few years. So, it's never safe to touch a capacitor with your hands and you should make sure to discharge any capacitors in a circuit before working on it using an appropriately high-wattage resistor or a capacitor discharge tool.
Current is the rate of flow of electrons per unit time and is measured in:
volts |
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coulombs |
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amperes |
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ohms |
Current is the rate of flow of electrons per unit time and is measured in amperes (A). A coulomb (C) is the quantity of electricity conveyed in one second by a current of one ampere.
The diameter of a number 12 wire is __________ the diameter of a number 6 wire?
more than |
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triple |
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less than |
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double |
The larger the number the smaller the diameter of the wire. So, the diameter of a number 12 wire is less than the diameter of a number 6 wire.