Final Exam - Study Guide - DC Circuits

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7 Οκτ 2013 (πριν από 3 χρόνια και 10 μήνες)

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DC Circuits
Study Guide for Chapters 27 and 28
It is likely that there will be a DC circuit question on the exam. I recommend studying the following two
topics:
 The relationship between energy and power.
 Resistors in series and in parallel (including complicated arrangements).
Kirchhoff's laws be required for the final exam.will not
Chapter 27: Current and Resistance
Electric current magnitude is the flow of electric charge. The of the current is the charge per
unit time that flows through the conductor:
M œ
U
>?
A is a circuit element that opposes the flow of electric current. When current flowsresistor
through a resistor, the result is a potential difference in the opposite direction:
Z œ MV
Here is the potential difference, is the current through the resistor, and is the .Z M V resistance
A forces current through a circuit by maintaining a constant potential difference acrossbattery
its leads. A battery adds energy to a circuit:
c œ MZ
Here is the  the amount of energy delivered per unit time. Power is measured inc power
watts, which are joules per second.
A resistor dissipates energy from the circuit:
c œ MZ œ M V œ
Z
V
#
#
In this equation represents the amount of energy dissipated per unit time:c
c
?
?
œ
>
a benergy
Problems:Chapter 27 # 1, 23, 27
Chapter 28: DC Circuits
When two resistors are in , their resistances :series add
V œ V V
total"#
When two resistors are in , the addition works diff erently:parallel
V œ
"

total
""
V V
"#
These rules can be combined to analyze more complic ated arrangements of resistors:
V œ V  V
"

total"'
""
V V V V
#$ % &
When these rules can be applied, they are much easier to use than Kirchhoff's laws.
The following problems all involve series and paral lel resistors. Do use Kirchhoff's laws tonot
solve these problems.
Problems:Chapter 28 # 5, 7, 9, 15