11.4 Chapter summary
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11.4 Chapter summary (ESBQH)
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Ohm's Law states that the amount of current through a conductor, at constant temperature, is proportional to the voltage across the resistor. Mathematically we write \(I = \frac{V}{R}\)
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Conductors that obey Ohm's Law are called ohmic conductors; those that do not are called non-ohmic conductors.
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We use Ohm's Law to calculate the resistance of a resistor. \(R = \frac{V}{I}\)
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The equivalent resistance of resistors in series (\(R_{s}\)) can be calculated as follows: \(R_{s} = R_{1} + R_{2} + R_{3} + \ldots + R_{n}\)
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The equivalent resistance of resistors in parallel (\(R_{p}\)) can be calculated as follows: \(\frac{1}{R_{p}} = \frac{1}{R_{1}} + \frac{1}{R_{2}} + \frac{1}{R_{3}} + \ldots + \frac{1}{R_{n}}\)
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Electrical power is the rate at which electrical energy is converted in an electric circuit.
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The electrical power dissipated in a circuit element or device is \(P=VI\) and can also be written as \(P=I^2R\) or \(P=\frac{V^2}{R}\) and is measured in joules (J).
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The electrical energy dissipated is \(E=Pt\) and is measured in joules (J).
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One kilowatt hour refers to the use of one kilowatt of power for one hour.
Physical Quantities | ||
Quantity | Unit name | Unit symbol |
Current (\(I\)) | Amperes | \(\text{A}\) |
Electrical energy (\(E\)) | Joules | \(\text{J}\) |
Power (\(P\)) | Watts | \(\text{W}\) |
Resistance (\(R\)) | Ohms | \(\text{Ω}\) |
Voltage (\(V\)) | Volts | \(\text{V}\) |
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11.3 Power and energy
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