circuitos cap 1 parte2

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Chapter 1 – Electric Circuit Variables 
Exercises 
Ex. 1.2-1 
( ) 2
2 3 2 3
0 0 0
 8 4 A
8 8( ) (0) (8 4 ) 0 2 2 C
3 3
tt t
i t t t
q t i d q d t tτ τ τ τ τ τ
= −
= + = − + = − = −∫ ∫ 2 
 
Ex. 1.2-2 
( ) 4sin 3 12cos3 Adq di t t t
dt dt
= = = 
 
Ex. 1.3-1 
i1 = 45 μA = 45 × 10-6 A < i2 = 0.03 mA = .03 × 10-3 A = 3 × 10-5 A < i3 = 25 × 10-4 A 
 
 
Ex. 1.5-1 
 (a) The element voltage and current do not adhere to the passive convention in 
Figures 1.5-1B and 1.5-1C so the product of the element voltage and current 
is the power supplied by these elements. 
(b) The element voltage and current adhere to the passive convention in Figures 
1.5-1A and 1.5-1D so the product of the element voltage and current is the 
power delivered to, or absorbed by these elements. 
(c) The element voltage and current do not adhere to the passive convention in 
Figure 1.5-1B, so the product of the element voltage and current is the power 
delivered by this element: (2 V)(6 A) = 12 W. The power received by the 
element is the negative of the power delivered by the element, -12 W. 
(d) The element voltage and current do not adhere to the passive convention in 
Figure 1.5-1B, so the product of the element voltage and current is the power 
supplied by this element: (2 V)(6 A) = 12 W. 
(e) The element voltage and current adhere to the passive convention in Figure 
1.5-1D, so the product of the element voltage and current is the power 
delivered to this element: (2 V)(6 A) = 12 W. The power supplied by the 
element is the negative of the power delivered to the element, -12 W. 
 
 
 
1-1