Series and Parallel Circuits
Test Review KEY
I. Complete the following:
1. Series circuits have only _ONE_ path. The __VOLTAGE__, __RESISTANCE __, and __ POWER _ add
around the circuit. The __CURRENT__ is constant.
2. Parallel circuits have _MORE__ _THAN__ one path. The _CURRENT__ and __POWER__ add around the
circuit. The resistance __RECIPROCALS___ add to give the _RECIPROCAL__ resistance. The
_VOLTAGE__ is constant.
3. To solve circuit problems set up a _CHART_. Fill in the information that is _GIVEN__ and _GIVEN__ for
that type of circuit. Use _OHM’S_ _LAW__ to complete columns and the _CHARACTERISTICS___ of that
type of circuit to complete _ROWS_.
4. Complex or _COMBINATION__ circuits have parts that are connected in _SERIES_ and parts that are
connected in __PARALLEL_. To find the values in these circuits create a _CHART_, keep simplifying until
you have a _SERIES__ circuit, and then solve using the _CHARACTERISTICS_ for series and parallel.
5. When you add cells in series, _POSITIVE_ terminals are connected to _NEGATIVE_ terminals.
_CURRENT_ is constant. _EMF_ and _TERMINAL___ __VOLTAGE__ adds. The result is _HIGH_
voltage over a _SHORT__ period of time.
6. When you add cells in parallel, __POSITIVE__ terminals are connected to _POSITIVE__ terminals.
_EMF__ is constant. _CURRENT_ adds and the reciprocals of internal _RESISTANCES__ add to give the
reciprocal of the internal resistance. Provides __VOLTAGE___ over a __LONG___ period of time.
7. All batteries have _INTERNAL__ resistance because __ENERGY_ is used to drive the _CURRENT_
through the battery. The _ELECTROMOTIVE___ _FORCE_ (EMF) is the amount of _OPEN__ circuit
energy. The _TERMINAL__ _VOLTAGE_ (VT) is the _CLOSED__ circuit reading and is always less than the
_EMF_ due to the internal _RESISTANCE_.
8. Kirchhoff’s First Law states that the _TOTAL_ current into a junction is _EQUAL__ to the _TOTAL_
current leaving the junction because of the _LAW_ of conservation of __CHARGE_.
9. Kirchhoff’s Second Law states that the algebraic _SUM_ of the changes in potential _DIFFERENCE_
occurring in any closed loop is _ZERO_ due to the _LAW_ of conservation of _ENERGY_.
10. The sign conventions for Kirchhoff’s 2nd Law are: crossing a battery with current _+_V, against _-_ V
and crossing a resistor with current _-_ IR, against current _+_ IR.
II. True or False:
T
T
T
T
T
F
F
F
F
F
Adding a resistor to a parallel circuit decreases the total resistance.
If one resistor is turned off in a series circuit, the current through all the other resistors remains the same.
In a parallel circuit, the smallest resistor dissipates the most power.
The voltage drop across a resistor in a series circuit is proportional to its resistance.
Adding a resistor to a series circuit decreases the total resistance.
III. Complete the tables/Fill in all blanks:
R2 = 1000 
R1 = 500 Ω
50 V
R2 = 500 Ω
50 V
R1 = 500 Ω
R3 = 1000 
R3 = 1000 Ω
V
I
R
P
T
50
0.025
2000
1.25
1
12.5
0.025
500
0.3125
2
12.5
0.025
500
0.3125
3
25
0.025
1000
0.625
R2 = 1000 
V
I
R
T
100
0.1
1000
1
50
0.1
500
5
2
50
0.05
1000
2.5
3
50
0.05
1000
2.5
R3 = 500 
R1 = 500 
100 V
T
50
0.2
250
10
V
I
R
P
1
50
0.1
500
2
50
0.05
1000
Top Loop Equation:
-30+56000I1+68000I2=0
Bottom Loop Equation:
-47000I3-68000I2+40=0
R4 = 500 
3
25
0.05
500
I2
4
25
0.05
500
Equation:
I1 = I2+I3+I4+I5
I3
I1
I4
I5
If I1 = 50 A
I2 = 8 A
I3 = 12 A
I4 = 20 A
Then, I5 = _10_ A
IV. Solve the following problems: (Use a separate sheet of paper, show work including table.)
1. Two lamps having a resistance of 100 Ohms and 200 Ohms are connected in series across a 150 V battery.
What is the current through the lamp? What is the voltage drop across each resistor?
T
1
2
V
150
50
100
I
0.5
0.5
0.5
R
100
200
300
2. Four resistors of equal value are in parallel, with 120 V across them. The total current is 2 A. Determine the
value of each resistor.
T
1
2
3
4
V
120
120
120
120
120
I
2
0.5
0.5
0.5
0.5
R
60
240
240
240
240
3. In a kitchen, three 75 W bulbs are connected in parallel across 120 V. All three bulbs are on. At 6:00 am, a
360 W coffeepot also in parallel is turned on. Calculate the total current drawn.
V
I
R
P
T
120
4.875
1
120
0.625
2
120
0.625
3
120
0.625
4
120
3
585
75
75
75
360
4. The terminal voltage of a 24-V battery is 22.0 V and the current in the circuit is 2.00 A. What are the internal
resistance of the battery and the resistance of the circuit resistor?
24 – 22 = 2 ri ri = 1 Ohm
22 = 2 RT
RT = 11 Ohms
5. A dry cell has an EMF of 1.5 V and an internal resistance of 0.2 Ω. If the terminal voltage is 1.2 V, what
current is delivered to the external circuit?
1.5 – 1.2 = I (0.2)
I = 1.5 Amps
Answers to problems: 1. 0.5A, 50V, 100V
2. 240 ea.
3. 4.875A
4. 1, 11
5. 1.5A