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MECH1310Chapter4Homework

True/False
Indicate whether the statement is true or false.
 

 1. 
In a series circuit, the current is the same at every point in the circuit.
 

 2. 
Kirchhoff's Voltage Law states that the algebraic sum of all the voltages around a closed path is zero.
 

 3. 
The total power dissipated in a series circuit equals the sum of the individual powers.
 

 4. 
If 6.8 kÙ, 1.2 kÙ and 5.6 kÙ resistors are wired in series, the total resistance is 13.6 kÙ.
 

 5. 
If 4.7 kÙ, 2.2 kÙ and 1.2 kÙ resistors are wired in series, the total resistance is 8.7 kÙ.
 

 6. 
Total power dissipated in a series circuit equals source voltage multiplied by current.
 

 7. 
If a resistor is rated at 1/2 W, it can safely dissipate 0.325 W.
 

 8. 
According to Kirchhoff's Voltage Law, the sum of the individual voltage drops in a series circuit equals the source voltage.
 

 9. 
A series circuit has multiple current paths.
 

 10. 
Three 2 V cells in series with one in series-opposing would yield 2 V.
 

Multiple Choice
Identify the choice that best completes the statement or answers the question.
 

 11. 
What is the total resistance in Figure 4-1 if R1 = 10 kÙ, R2 = 10 kÙ and R3 = 15 kÙ?
mc011-1.jpg
Figure 4-1
a.
0 kÙ
c.
35 kÙ
b.
25 kÙ
d.
infinite Ù
 

 12. 
Calculate the current in Figure 4-1 if VR1 = 16 V, R1 = 10 kÙ, R2 = 10 kÙ and R3 = 15 kÙ.
mc012-1.jpg
Figure 4-1
a.
3.2 mA
c.
12 mA
b.
0 A
d.
1.6 mA
 

 13. 
Calculate VR2 and VR3 in Figure 4-1 if VR1 = 16 V, R1 = 10 kÙ, R2 = 10 kÙ and R3 = 15 kÙ.
mc013-1.jpg
Figure 4-1
a.
VR2 = 16 V, VR3 = 16 V
c.
VR2 = 16 V, VR3 = 12 V
b.
VR2 = 24 V, VR3 = 12 V
d.
VR2 = 16 V, VR3 = 24 V
 

 14. 
Calculate PR2 in Figure 4-1 if VR1 =16 V, R1 = 10 kÙ, R2 = 10 kÙ and R3 = 15 kÙ.
mc014-1.jpg
Figure 4-1
a.
0.0256 mW
c.
25.6 mW
b.
2.56 mW
d.
0.256 mW
 

 15. 
Calculate VT in Figure 4-1 if VR1 = 16 V, R1 = 10 kÙ, R2 = 10 kÙ and R3 = 15 kÙ.
mc015-1.jpg
Figure 4-1
a.
112 V
c.
24 V
b.
56 V
d.
16 V
 

 16. 
VR1 = 16 V, R5 = 10 kÙ, R2 = 10 kÙ and R3 = 15 kÙ in Figure 4-1. If R2 opens, then RT is ________.
mc016-1.jpg
Figure 4-1
a.
0 Ù
c.
25 kÙ
b.
10 kÙ
d.
infinite Ù
 

 17. 
If R2 opens in Figure 4-1, the total power dissipated ________.
mc017-1.jpg
Figure 4-1
a.
remains the same
c.
decreases to zero
b.
increases to maximum
d.
will depend upon the source voltage
 

 18. 
Calculate PT in Figure 4-1 if VT = 100 V and all three resistors are each 47 kÙ.
mc018-1.jpg
Figure 4-1
a.
22 W
c.
23.6 mW
b.
70.9 mW
d.
709 mW
 

 19. 
Calculate VR3 in Figure 4-1 if VT = 50 V, VR1 = 19.7 V and VR2 = 2.7 V.
mc019-1.jpg
Figure 4-1
a.
30.3 V
c.
27.6 V
b.
47.3 V
d.
22.4 V
 

 20. 
How much voltage is dropped across R2 and R3 in Figure 4-1 if R1 = 4.7 kÙ, VR1 = 10 V, R2 = 4.7 kÙ and R3 = 4.7 kÙ?
mc020-1.jpg
Figure 4-1
a.
VR2 = 4.7 V, VR3 = 10 V
c.
VR2 = 10 V, VR3 = 4.7 V
b.
VR2 = 10 V, VR3 = 10 V
d.
VR2 = 14.7 V, VR3 = 14.7 V
 

 21. 
Calculate IT in Figure 4-1 if R1 = 4.7 kÙ, VR1 = 10 V, R2 = 4.7 kÙ and R3 = 4.7 kÙ.
mc021-1.jpg
Figure 4-1
a.
2.13 mA
c.
1 mA
b.
6 mA
d.
4.26 mA
 

 22. 
Calculate VT in Figure 4-1 if R1 = 4.7 kÙ, VR1 = 10 V, R2 = 4.7 kÙ and R3 = 4.7 kÙ.
mc022-1.jpg
Figure 4-1
a.
30 V
c.
14.7 V
b.
4.7 V
d.
10 V
 

 23. 
If R2 shorts in Figure 4-1, the total circuit power ________.
mc023-1.jpg
Figure 4-1
a.
remains the same
c.
depends upon the source voltage
b.
decreases
d.
increases
 

 24. 
R1 = 4.7 kÙ, R2 = 4.7 kÙ and R3 = 4.7 kÙ in Figure 4-1. What is RT if R2 shorts?
mc024-1.jpg
Figure 4-1
a.
0 Ù
c.
4.7 kÙ
b.
9.4 kÙ
d.
infinite Ù
 

 25. 
What is the total supply voltage if 16 V and 12 V sources are wired in series opposing?
a.
12 V
c.
28 V
b.
4 V
d.
16 V
 

 26. 
If 12 V and -19 V sources are connected so their total voltage is -7 V, they are ________.
a.
in parallel
c.
series aiding
b.
series opposing
d.
connected dangerously
 

 27. 
Based upon electron current flow, the polarity on the side of the resistor where current enters is ________. The polarity on the side of the resistor where current exits is ________.
a.
positive, negative
c.
negative, positive
b.
negative, negative
d.
positive, positive
 

 28. 
When 50 V is applied to four series resistors, 100 ìA flows. If R1 = 12 kÙ, R2 = 47 kÙ and R3 = 56 kÙ, what is the value of R4?
a.
3.85 MÙ
c.
38.5 kÙ
b.
3.85 kÙ
d.
385 kÙ
 

 29. 
If R1 = 12 kÙ and R2 = 5 kÙ and they are wired in series across a 20 V source, what is VR1 and VR2?
a.
VR1 = 0 V, VR2 = 20 V
c.
VR1 = 14.12 V, VR2 = 5.88 V
b.
VR1 = 5.88 V, VR2 = 14.12 V
d.
VR1 = 10 V, VR2 = 10 V
 

 30. 
Four resistors are connected in series across an 18 V source. Three resistors drop 0 V and one resistor drops 18 V. What's the trouble?
a.
The three resistors are open.
b.
One resistor is open.
c.
Two of the resistors are shorted.
d.
There is no trouble; these voltages are normal.
 

 31. 
If 12 V and 17 V sources are wired in series aiding, what is the total supply voltage?
a.
29 V
c.
12 V
b.
5 V
d.
17 V
 

 32. 
Two 100 kÙ resistors are wired in series across a 20 V source. How much voltage does each resistor drop?
a.
10 V
c.
20 V
b.
100 kÙ
d.
100 mA
 

 33. 
A 22 kÙ and 12 kÙ resistor are connected across a 68 V source. How is the voltage divided?
a.
68 V and 68 V
c.
34 V and 34 V
b.
22 V and 12 V
d.
44 V and 24 V
 

 34. 
A 500 kÙ potentiometer is connected across a 5 V source. If the voltage from the wiper to the lower end of the potentiometer is 1.2 V, what is the resistance of that lower part?
a.
500 kÙ
c.
380 kÙ
b.
0 Ù
d.
120 kÙ
 

 35. 
-1.2 V, +5 V and +6 V batteries are connected in series. The total voltage is ________.
a.
9.8 V
c.
1.3 V
b.
1.2 V
d.
12.2 V
 

 36. 
If a 100 Ù, 220 Ù, and 330 Ù resistor are connected in series, total resistance equals ________.
a.
1650 Ù
c.
650 Ù
b.
the average of the three values
d.
less than 100 Ù
 

 37. 
If a 68 Ù, 33 Ù, 100 Ù and 47 Ù resistor are connected in series across a 9 V battery, the current equals ________.
a.
22.3 mA
c.
327 mA
b.
27.6 A
d.
36.3 mA
 

 38. 
If each of the six resistors in a series circuit drops 5 V, the source voltage ________.
a.
equals 30 V
c.
depends on the current
b.
depends on the resistor values
d.
equals 5 V
 

 39. 
If a 4.7 kÙ, 5.6 kÙ and 10 kÙ resistor are in series, which resistor drops the most voltage?
a.
the 4.7 kÙ resistor
b.
the 10 kÙ resistor
c.
the 5.6 kÙ resistor
d.
That can't be determined from the given information.
 

 40. 
If five equal resistors dissipate a total of 10 W in a series circuit, how much power does each resistor dissipate?
a.
5 W
c.
2 W
b.
10 W
d.
50 W
 

 41. 
If 18 V and 6 V sources are connected in series opposing, what is the total voltage?
a.
6 V
c.
18 V
b.
2 V
d.
12 V
 

 42. 
If three 2.2 kÙ resistors are connected in series across a 50 V source, PT equals ________.
a.
52.08 mW
c.
402 mW
b.
104.2 mW
d.
379 mW
 

 43. 
Three resistors are connected in series across a 60 V source. If VR1 = 19 V and VR2 = 14.3 V, then what is the voltage drop across R3?
a.
45.7 V
c.
19 V
b.
14.3 V
d.
26.7 V
 

 44. 
If 5 V and 16 V power supplies are connected in series aiding, what is the total voltage?
a.
24 V
c.
16 V
b.
21 V
d.
80 V
 

 45. 
Two resistors are in series across a 12 V source. If each resistor equals 470 kÙ, what is the voltage across each resistor?
a.
3 V
c.
12 V
b.
6 V
d.
9 V
 

 46. 
If a 10 kÙ and 5 kÙ resistor are connected in series across a 12 V source, the voltage across the 10 kÙ resistor is ________ and the voltage across the 5 kÙ resistor is ________.
a.
8 V, 8 V
c.
4 V, 8 V
b.
8 V, 4 V
d.
4 V, 4 V
 

 47. 
Four series resistors are connected across a 30 V source and carry 0.125 mA. If R1 = 10 kÙ, R2 = 33 kÙ and R3 = 47 kÙ, what is the value of R4?
a.
15 kÙ
c.
1.5 kÙ
b.
150 Ù
d.
150 kÙ
 

 48. 
The voltage drop across any resistor or combination of resistors in a series circuit equals:
a.
the applied voltage across the resistor (A).
b.
the product of the circuit current times the resistance value.
c.
the ratio of the resistance values to the total resistance times the source voltage.
d.
all of these.
 

 49. 
A 50 kÙ potentiometer is connected across a 15 V source. If the voltage from the wiper to the lower end of the potentiometer is 3.2 V, what is the resistance of that lower part?
a.
39.3 kÙ
c.
0 Ù
b.
10.7 kÙ
d.
50 kÙ
 

 50. 
One of the most popular applications of a potentiometer is as an adjustable voltage divider also known as a:
a.
voltage control.
c.
current control.
b.
volume control.
d.
divider control.
 

 51. 
In a series circuit, total power PT is calculated as:
a.
P1 × P2 × P3 × etc.
c.
P1 + P2 + P3 + etc.
b.
P1 ÷ P2 ÷ P3 ÷ etc.
d.
1/P1 + 1/P2 + 1/P3 + etc.
 

 52. 
In a series circuit, the largest amount of power is dissipated by:
a.
the largest resistor.
b.
the first resistor.
c.
the smallest resistor.
d.
any resistor, since the current is the same throughout the circuit.
 

 53. 
An open in a series circuit results in:
a.
no current flow.
b.
source voltage appearing across the open.
c.
no power dissipation.
d.
all of these.
 

 54. 
A short in a series circuit results in:
a.
decreased or reduced current flow.
c.
increased circuit resistance.
b.
decreased power consumption.
d.
increased or maximum current flow.
 

 55. 
Refer to Figure 4-2a. Voltage B to ground is less than normal. What could be the cause of failure?
mc055-1.jpg
Figure 4-2a
a.
short between E and D
c.
open between C and D
b.
open between B and C
d.
short between A and B
 

 56. 
Refer to Figure 4-2a. Voltage from C to ground is 100 V. What is the probable cause of failure?
mc056-1.jpg
Figure 4-2a
a.
short between A and B
c.
open between A and B
b.
open between E and D
d.
voltage reading is normal
 

 57. 
Refer to Figure 4-2a. The resistor between points E and D looks charred. What most likely would cause this?
mc057-1.jpg
Figure 4-2a
a.
open A and the power supply
c.
short between A and B
b.
short between A and D
d.
Any of these could cause this problem.
 

 58. 
What type of resistor could be used as variable voltage-divider?
a.
rheostat
c.
thermistor
b.
potentiometer
d.
any one of the above
 

 59. 
What is the easiest, most practical measurement performed during troubleshooting?
a.
power
c.
voltage
b.
resistance
d.
current
 



 
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