Unformatted text preview: 7""— 19. For constant resistances, voltage is proportional to
current. If the current and voltage references have
the passive conﬁguration, Ohm’s law states that Problems Section 1.1: Overview of Electrical Engineering PL]. List four reasons why other engineering stu~
dents need to learn the fundamentals of elec
trical engineering. Pl.2. List eight subdivisions of electrical engineering. Section 1.2: Circuits, Currents, and Voltages PL3. Carefully deﬁne or explain the following terms
in your own Words (give units where appropri
ate): 3. Electrical current. I). Voltage. c. An
open switch. (I. A closed switch. e. Direct cur—
rent. f. Alternating current. Pl.4. In the ﬂuidﬂow analogy for electrical circuits.
what is analogous to a. a conductor: b. an open
switch; c. a resistance; d. a battery. Pl.5. The charge of an electron is —l.60 x 10“9 C.
A current of J A ﬂows in a wire carried by elec
trons. How many electrons pass through a cross
section of the wire each second? in 3 seconds? *PIJ. The net charge through a cross section of a cir—
cuit element is given by q(r) = 2 + 3: C. Find
the current through the element. Pl.8. The current through a particular circuit element
is given by t0) = 10 sin(200:rr) A in which the
angle is in radians. 3. Sketch i (r) to scale versus
time. b. Determine the net charge that passes
through the element between I = 0 and r =
5 ms. c. Repeat for the interval from r = 0 to
r = 10 ms. ——___
Denotes that answers can be found on the OrCAD CD and on the website www . prenhall .com/hamb l ey It a Problems 39 v = Rf. For references opposite to the passive
configuration. v = —R:'. *Pl.9. The current through a given circuit element is
given by [(1): 29“ A Find the net charge that passes through the ele
mentin the interval from r = 0 tor = 00. (Hint: PLIO. The net charge through a cross section of a cer
tain circuit element is given by q(f) = 3 , 353' C Determine the current through the element. PL] 1. A copper wire has a diameter of 2.05 mm and the electrons in the wire. Pl.]2. An electron moves through a voltage of 9 V
from the positive polarity to the negative polar
ity. How much energy is transferred? Does the
electron gain or lose energy? * Pl.l3. A typical “deepcycle" battery (used for electric
trolling motors for ﬁshing boats) is capable of
delivering 12 V and 5 A for a period of 10 hours.
How much charge ﬂows through the battery in
this interval? How much energy is delivered by
the battery? ...
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 Fall '06
 Preston

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