T01Example

# T01Example - Example 2: (From P1-20, Circuits, Devices and...

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Example 1: (From Ex1.24, Electric Circuits, 5 th Ed. Nilsson/Riedel) a) In the circuit shown in Fig. 1, identify which elements have the voltage current reference polarities defined using the passive sign convention. b) The numerical values of the for each elements are given in Table 1 How much total power is absorbed and how much is delivered in this circuit? Element a b c d e f g h Voltage (V) 5 1 7 - 9 - 20 20 - 3 - 12 Current (A) 2 3 - 2 1 5 2 - 2 - 3 Answers to Example 1: a) Based on the reference polarities shown, the following elements employ the passive convention: a, e, f, and h. b) P a = 5 × 2 = 10W (abs) P b = - 1 × 3 = - 3W (del) P c = - 7 × ( - 2) = 14W (abs) P d = - ( - 9) × 1 = 9W (abs) P e = ( - 20) × 5 = - 100W (del) P f = 20 × 2 = 40W (abs) P g = - ( - 3) × ( - 2) = - 6W (del) P h = ( - 12) × ( - 3)= 36W (abs) = + + + + = 109W 36 40 9 14 10 abs P = + + = 109W 6 100 3 del P a g d b h e f c + v a - i a - v b + i b - v g + i g + v h - i h - v c + i c + v d - i d i e + v e - - v f + i f Fig. 1 Table 1

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Total power of absorb = Total power delivered. Energy is conserved in this circuit.
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Unformatted text preview: Example 2: (From P1-20, Circuits, Devices and Systems by Smith and Dorf) The current source in Fig 2 provides an output defined by I=5t A. where t is in seconds. For time t = 2s calculate: a) The power dissipated if R = 15 Ω . b) The power of inductor if L = 10H. c) The power delivered by the source. d) The total energy dissipated in the resistor. e) The total energy stored in the inductor. Answers to Example 2: a) W R I IV P R 1500 15 10 2 2 = × = = = b) W dt dI L I IV P L 500 5 10 10 = × × = × = = c) W P P P L R s 2000 = + = d) J t dt t dt t dt R I dt P E R R 1000 3 375 375 15 25 2 3 2 2 2 2 2 2 2 = = = × = = = ∫ ∫ ∫ ∫ J LI IdI L dt dt dI L I dt P E L L 500 2 1 2 2 2 2 = = = × = = ∫ ∫ ∫ I(t) R L Fig. 2...
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## This note was uploaded on 10/28/2011 for the course ELEC 101 taught by Professor Chan during the Spring '09 term at HKUST.

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T01Example - Example 2: (From P1-20, Circuits, Devices and...

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