CIRCUITS WORKSHEET
1. Determine the equivalent (total) resistance for each of the following circuits below.
a
70
Req =Egret
________
22
Req = ________
72
Is
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Req = ________
142
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2. Determine the total voltage (electric potential) for each of the following circuits below.
TTelectric
BV
potential difference across each
resistor
akacurrent
RV
7
3. In a series circuit there is just one path so the charge
flow is constant everywhere (charge is not lost or
gained). CircuitB was made by adding 2 more
identical resistors in series to circuitA
Rega
R
R
I=3A
a) How is the charge flow out of the battery (and
back into it) affected by adding more bulbs in
series? Thecurrent in B
is
IB
three times smaller than Ia
+
Regz
3R
R
R
R
- Ia IB
R
+
- I z NB_
Circuit B
Circuit A
IB BIA
3R
b) If the resistors were light bulbs, how do you expect the brightness of the bulbs to be affected by adding
more bulbs in series?
dimmer
will
They
get
c) How is the brightness in the 2 circuits related to charge flow or current?
Morecurrent the brighter the bulbs
d) How does the current in circuit B compare to circuit A?
Thecurrent in B IB is
three times smaller than Ia
e) How is current (I) related to the resistance of the circuit?
IE Erb
inversely
ega circuit is quadrupled, by what factor does the current change?
f) If the resistance of
Ax smaller for bulbs in series
OV IbR 0.10402 IV
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g) Fill out the table for the circuit diagramed at the right.
VzIbR3
Circuit
Position
R
Rz
Rz
1
2
3
ahffeguythlyTotal
diff.OVCurrent
pot
Voltage
(V)
N
IV
3V
6.00
26102 0 IOA
Ib
powerconsumption
IoV (W)
p Power
Rly
(A)
Resistance
(Ω)
0.10A
10.0
0.10W
0.10A
0.10A
20.0
0.20W
0.30W
0.60W
0.10A
30.0
602
R2
R1
R3
-
+
h) Is there a relationship between resistance and voltage drop in a series circuit? If so, state it.
DVbulb
IbulbXRbulb
c) If the resistors were light bulbs, explain in terms of charge flow (current) and energy per charge (voltage)
which bulb would be brightest / dimmest.
There is the greatest voltage drop (loss of energy per charge) across the bulb with the highest resistance. The bulb with the
highest resistance would be the brightest because the charges are “losing” the most energy through the filament (as
compared to a bulb with a lesser resistance).
4 a - c.The Req in B is less
than in A, so the current in
B through the battery is
4. In a parallel circuit, there is more than one loop or
greater than current in A
pathway so charge flow gets split up or recombined through the battery. Current
at junction points. Therefore current is not the same through the battery in B is
equal to the sum of the
at every point in the circuit
current in each branch in B.
Current is the same in any
a) How does the current through the one resistor in part of wire in A.
3W
3W
circuit A, compare to the current through each
resistor in circuit B? (Use Kirchoff Loop rule on
circuit B to look at the current in each path.)
3W
This isbasiallythefbenyou.ir
I = ____
book on page 1046
b) How does the sum of the currents through the
three bulbs in circuit B compare to current from
the battery in circuit A?
c) How is the current out of the battery (and back
into it) affected by adding resistors in parallel? Explain
+
6V
-
Circuit A
3W
I = ____
-
+
6V
Circuit B
d) If the resistors were light bulbs, how does the brightness of each bulb in circuit B compare to the
brightness of the single bulb in circuitA,?
The bulbs in B would be just as bright as the bulbs in A. The current through the bulb in A is 2A.
The current through the battery in B is 6A, but current through each bulb in B is 2A. The potential
difference across the bulb in A is -6V. The potential difference across each bulb in B is -6V.
e) How is the resistance of a circuit affected by adding additional pathways?
Ib
6I
5 EE
EVb
Reg
The Req goes down when you add more pathways (e.g. parallel circuit)
lApot.diff.oVI
f) Fill out the table for the circuit diagramed at the right.Leg
Circuit
Position
Voltage
(V)
1
W
tell
2
3
hbhaffeguythesTotal
6V
6.00
oI
R
Current (A)
0.6A
0.3A
0.2A
1.1A
otrttzaztgtojftor.BEffz 5.5r
Resistance PowPower (W)Ampeg
(Ω)
A LOV
10.0
20.0
30.0
5.51
R3
3.6W
1.8W
1.2W
R2
6.6W
R1
g) How does the voltage drop across each branch in a parallel circuit compare?
The same
+
-
h) If the resistors were light bulbs, explain in terms of charge flow (current) and energy per charge (voltage)
which bulb would be brightest / dimmest.
Energy per charge across each bulb is the same (∆V), but current through each bulb is not the same. The 10Ω bulb has the
most current through it so it would be the brightest. The 30Ω bulb has the least amount of current through it so it would be
the dimmest.
5. Consider the circuit at right. Assume the resistors are identical.
a) Rank the resistors according to the flow of charge through them.
R
Rz Rz
b) Imagine that the resistors in parallel (R2 and R3) were a single resistor.
How would the combined equivalent resistance of R23 compare to the
resistance of R1?
The combined Req of bulb 2 and 3 would be less than the resistance of bulb 1. If these were 1Ω resistors, then R1 would
have a resistance of 1Ω, and Req of bulbs 2 and 3 in parallel would be 1/2Ω.
Reganwould beexactly half of
R
c) Now let R1 = 10 W, R2 = 20 W and R3 = 30 W Fill out the table for the circuit
consumption
Circuit potdifferencoV
Voltage
Resistance power
Power (W)
they
Current (A)
Position
(V)
(Ω)
f
1
2
2.7N 0.27A
3.2N
0.16A
3
3mV 0.11A
hbhaffegyh.tk Total
0.27A
b 6.00
OVFIIRi O27AHOD 2TV
Iz I kV 2 I33 0.16A
Iz
3jfIr 0.11A
10.0
20.0
30.0
121
lov
0.73W
Tortfor foffth
Reyez _122
0.53W Regi
lost 121 222
0.36W
Oo27A
1.62W Ib NpqTµ
r
Questions 6 and 7 refer to the following:
The diagram to the right represents an electric
circuit consisting of four resistors and a 12-volt
battery.
I
2
6) What is the equivalent resistance of the circuit shown?
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7) What is the current measured by ammeter A shown in the diagram?
0Y
L2V
2A
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3
fr
r ampere
z of current to operate. In which circuit below would the lamp operate
8) A 6.0-ohm lamp requires 0.25
correctly when switch S is closed?
0.25A
Ib fIef
fihortif
shortcircuit
short circuit
Questions 9 and 10 refer to the following:
A 50.-ohm resistor, an unknown resistor R, a 120-volt source, and an ammeter are connected in a complete
circuit. The ammeter reads 0.50 ampere.
9) Calculate the equivalent resistance of the circuit shown. Reg
10) Determine the resistance of resistor R shown in the diagram.
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t2
124027
R 2402 502 119027
Questions 11 through 13 refer to the following:
A 3.0-ohm resistor, an unknown resistor, R, and two ammeters, A1 and A2, are connected as shown below with a
12-volt source. Ammeter A2 reads a current of 5.0 amperes.
11) Determine the equivalent resistance of the circuit shown.
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Ift
42.41
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In
12) Calculate the current measured by ammeter A1 in the diagram shown.
13) Calculate the resistance of the unknown resistor, R in the diagram shown.
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14. A 110-V household circuit that contains an 1800-W microwave, a 1000-W toaster, and an 800-W
coffeemaker is connected to a 20-A fuse. Determine the current. Will the fuse melt if the microwave and the
coffeemaker are both on?
12 ir Rt3
3R
12.4kt7.21 3 R4R
2
I 2.4R
61
172
0.61
SKIP
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076
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RI
14. Determine the equivalent resistance of two resistors of 12 W and 18 W when they are connected
a) in parallel
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b) in series
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15) Assume that you have five one thousand ohm (1000 W) resistors.
a) Devise a circuit with an equivalent resistance of 1333 ohms.
1 in series 3 in parallel
10002
t
Reef
so
01
1003
33352
1,3332
b) Devise a circuit with an equivalent resistance of 750 ohm
c) Using all five resistors, what is the smallest resistance that can be constructed?
A
in
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Reg 2001
d) Using all five resistors, what is the largest resistance that can be constructed?
in series Reg 10002110001 Hovortlowrtlows
Rey 5,0002
16. Given the circuit at right:
24W
14
a) Draw the current flow on the circuit. Label
each current
3W
12
18
10W
1
8W
16
110
ar
13
It
6W
15W
19
5W
1z
I1=3A
xt24trtzgIp3_Ey
3W
b) Find the equivalent resistance, Req, of the circuit
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3
r
62
arttter Feather Fazio Fer
62
Rea
122
62
3
rt3
rt
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c) Complete the table
R (W)
Battery
3
3
24
8
10
15
6
5
V (v)
I (A)
39.43V
3
brRsr3A3r 9V
P (W)
lbReg 3A43ttr
5.14W
1.71A
10.3 V
0.93A
10.3W
1.3A
77V
0.76A
fFfe
77V
0.51A
same
7 GV
1.3A
l5rR5r 3Al5r l5V 3A
27W
8.8W
4 A W
13.4W
5.9W
10.1W
9
Answers
1a) 1.2 W
1b) 7 W
1c) 14 W
2a) 13 V
2b) 12 V
6) 3.0 W
7) 2.0 A
8) C
9) 240 W
10) 190 W
11) 2.4 W
12) 4.0 A
13) 12 W
14a) 350. W
14b) 0.143 A
14c) 17.9 V
15b) 60. W
15c) 0.20 A
16a) 0.10 A
16b) 400 W
16c) 40. W
17a) 680 W
17b) 0.018 A
17c) 2.2 V
18) 7.2 W
19) 4.0 W
20a) 36 W
20b) I62W = 0.19 A; I88W = 0.14 A
21) I = 23.6 A so fuse will melt
22a) 17 W
22b) I35W = 1.0 A; I55W = 0.64 A; I85W = 0.41 A
23b) 6.0 W
23c) 0.75 A
23d) 2.3 V
24b) 20.0 W
24c) 6.0 A
24d) 3.0 A
24e) 90. V
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step 4
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7.8 V
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step 5
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