| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.33 |
| Score | 0% | 67% |
From what energy do photovoltaic cells produce electrical energy?
chemical |
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magnetic |
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nuclear |
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sun |
A photovoltaic cell (also known as a solar cell) converts energy from the sun into electrical energy.
A capacitor is often used for which of the following purposes?
as a primary power source |
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to maintain power in a circuit when the primary power source is disconnected |
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to convert alternating current into direct current |
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to allow a small amount of current to control a large amount of current |
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.
Which of the following is the formula for calculating electrical power?
\(P = {V \over I}\) |
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\(P = {I \over V}\) |
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P = IV |
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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.
You would measure the amount of voltage between two points in a circuit with a(n):
reostat |
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voltmeter |
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ammeter |
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battery |
Voltage (V) is the electrical potential difference between two points. A voltmeter is used to measure the voltage between two points in a circuit.
Which of the following is not a common type of battery?
power-cycle |
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deep-cycle |
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dry cell |
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wet cell |
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 direct current (DC) is a battery. The three most common types of batteries are dry cell (used in small devices like TV remotes), wet cell (used for cars), and deep-cycle (storage batteries used primarily for backup and emergency power).