Circuit_Elements - Chapter 2 Circuit Elements There are...

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Chapter 2: Circuit Elements There are five Ideal Basic Circuit Elements. We defined this concept in an abstract way in the previous chapter; we make it more concrete here. The Ideal Basic Circuit Elements are as follows. Voltage source Current source Resistor Capacitor Inductor These circuit elements are used to model electrical systems, as we have suggested in Chapter 1. Note that these circuit elements are available in the laboratory. However, those in the lab are not ideal; they are “real” or, as your book calls them, “practical” circuit elements. When we draw circuit models on the board or in quizzes and exams, we assume that ideal elements are intended, unless otherwise stated. We will be discussing the difference between ideal and real circuit elements during the course. To solve circuits involving capacitors and inductors, we require differential equations. Therefore we will postpone these circuit elements until later in the course and deal for the moment with sources and resistors only. 2.1 Sources Source: a device capable of converting non-electrical energy into electrical energy. Examples: Dynamo Generator: mechanical electrical Motor: electrical mechanical
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The transformation between non-electrical and electrical energy is reversible, i.e., energy and power can bet either delivered or absorbed. We will deal with two kinds of sources: Dependent and Independent Dependent Source : a source whose value (voltage, current) depends on a voltage or current elsewhere in the circuit. Independent Source : a source whose value does is independent of any other voltages or currents in the circuit. Ideal Independent Voltage Source The ideal independent voltage source maintains a fixed voltage across its terminals regardless of the current through it. Thus it is completely defined by the fixed voltage. Ideal Independent Current Source The ideal independent current source maintains a fixed current through its terminals regardless of the voltage across it. Thus it is completely defined by the fixed current. v s i s
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Ideal Dependent Voltage Source The ideal dependent (or controlled) voltage source maintains a voltage across its terminals that depends on either a voltage or current elsewhere in the circuit. Thus x s v v μ = or x s i v ρ = where v x (i x ) is a voltage (current) somewhere else in the circuit, and μ and ρ are constants. Also note that μ is dimensionless but ρ has dimensions [Volts/Amp] (it multiplies a current but the resultant unit must be Volts). Ideal Dependent Current Source The ideal dependent (or controlled) current source maintains a current through its terminals that depends on either a voltage or current elsewhere in the circuit. Thus x s v i α = or x s i i β = where v x (i x ) is a voltage (current) somewhere else in the circuit, and α and β are constants. Also note that β is dimensionless but α has dimensions [Amps/Volt] (it multiplies a voltage but the resultant unit must be Amps).
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Circuit_Elements - Chapter 2 Circuit Elements There are...

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