US Army - Basic Principles of Alternating Current and Direct Current TC 9-60.pdf
Alternating Current vs. Direct Current
Transcript of Alternating Current vs. Direct Current
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Alternating Current
Direct Current
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Components of Electrical System
Voltage = term used to designate electrical pressure or force that causes
current to flow
Voltage source = generator/batteries
Conductor = wires
Control Element = switch
Load = light bulb, motors, appliances
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Direct Current (DC)
The first type of current because it was easy
to produce.
Type of current always flows in one direction
One of the disadvantages of using DC is theexcessive voltage drop and power loss in the
power lines in a long distance transmission.
Example: battery
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Alternating Current (AC)
s the solution to the problem of DC
Allows the flow of current in two directions
T!A"#$O!%E! & is the device used for
stepping'up or stepping'down AC voltage#tep'up to a power station( transmit it to any
distant place and step it down to for consumption
#ource: AC outlet ) **+ volts
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AC vs. DC
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O,%-# A/ A"D 0O/E!
A/
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O,%-# A/
#tates that: for a steady current1
the current in a circuit is directlproportional to the total E%$
acting in the circuit and in!erselproportional to the totalresistance of the circuit.
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O,%-# A/
The law may be expressed by the
following e2uation:
f the current I is in amperes
the electromotive force V is in volts
!esistance R is in ohms
Discovered by "eorg #imon $hm
3
! )
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#ample 0roblem 4:
/hat is the potential difference in an
electric circuit with a current of 45
amperes and a resistance of 6.+ ohms7
8iven: ) 45 A( ! ) 6.+ 9 $ind:3 ) 7
#ol-n: ) 3!( 3 ) ! 3 ) 45 A x 6.+ 9 );+ 3
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#ample problem *:
/hen a 4*'volt automobile battery is
connected across a resistor of un
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Exercise 4:
Estimate the resistance of the following
common household appliances1 assuming a
voltage of 4*+ 3 is applied across them:
a. A hair blower that has a current of 4+ A(
b. A >+'watt 3C! that carries a current of +.*5 A(
c. A corded electric ra?or that carries a current
of +.4+ A
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Exercise *:
,ow much current is drawn
from a 4*'volt battery when
a 45'ohm resistor isconnected across its
terminal7
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Exercise >:
/hat voltage must a
battery have to produce
+.5+ A of current througha *.+'ohm resistor7
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#eries and 0arallel
Circuits
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!esistance in #eries
Allow current to flow through one single path
#can page >@> physics boo@5 physics boo. The reciprocal of the total resistance or e2uivalent resistance in a parallel circuit
is e2ual to the sum of the reciprocals of the separate resistances.IT= I
1+ I
2+ I
3+ + I
N
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EECT!CA #B%O#
Wire
Switch
Lamp
Load
Battery
AC power
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