Question Bank in DC Circuits PDF

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Question Bank in DC Circuits A. 1895 ohms C. 1792 ohms B. 1825 ohms D. 1905 ohms A. DC CIRCUITS: BASIC PRINCIPLES 1. REE Board Exam March 1998 The substation bus bar is made up of 2 6. EE Board Exam April 1992 inches round copper bars 20 ft long. What is A copper wire of unknown length has a the res...

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Question Bank in DC Circuits A. DC CIRCUITS: BASIC PRINCIPLES 1. REE Board Exam March 1998 The substation bus bar is made up of 2 inches round copper bars 20 ft long. What is the resistance of each bar if resistivity is 1.724 x 10-6 ohm-cm. A. 7.21 x 10-5 Ω C. 5.185 x 10-5 Ω B. 13.8 x 10-6 Ω D. 2.96 x 10-5 Ω 2. REE October 1997 Determine the resistance of a busbar made of copper if the length is 10 meters long and the cross section is a 4 x 4 cm 2. Use 1.7241 micro ohm-cm as the resistivity. A. 2.121 x 10-4 Ω C. 3.431 x 10-5 Ω B. 4.312 x 10-4 Ω D. 1.078 x 10-4 Ω 3. EE Board Exam October 1991 One turn of a copper bar is produced by cutting copper washer along a radius and spreading the ends. The washer is cut from soft drawn copper having a resistivity at 20°C of 1.732 x 10-6 ohm-cm. The washer is 0.125 inch thick and has inside diameter and outside diameter of 1 inch and 9 inches respectively. Calculate the exact resistance between the two ends of the turn to direct current, taking into account the non-uniform current distribution. Assume the contact along the ends of the turn to be perfect over the entire cross section. A. 12.74 x 10-6 Ω C. 17.22 x 10-6 Ω B. 15.53 x 10-6 Ω D. 14.83 x 10-6 Ω 4. EE Board Exam October 1990 Determine the resistance of a conductor 0.10 m long, with a uniform diameter of 1.0 cm and having a resistivity which varies as a function of length L measured from the one end of the conductor according to ρ = 0.003 + 10-4 L2 ohm-cm. A. 0.0852 ohm C. 0.0806 ohm B. 0.0915 ohm D. 0.0902 ohm 5. EE Board Exam April 1992 A coil has 6,000 turns of wire and a resistance of 380 ohms. The coil is rewound with the same quantity (weight) of wire, but has 13,400 turns. How many ohms will the new coil have?

A. 1895 ohms B. 1825 ohms

C. 1792 ohms D. 1905 ohms

6. EE Board Exam April 1992 A copper wire of unknown length has a resistance of 0.80 ohm. By successive passes through drawing dies, the length of the wire is increased by 2 ½ times its original value. Assuming that resistivity remains unchanged during the drawing process, determine the new value of its resistance. A. 4 ohms C. 5 ohms B. 3 ohms D. 6 ohms

7. REE Board Exam October 1998 A one-meter rod of 2-cm diameter is drawn until its resistance is 100 times the initial resistance. Its length afterwards is? A. 10 m C. 12.5 m B. 100 m D. 5 m 8. EE Board Exam April 1993 A kilometer of wire having a diameter of 11.7 mm and a resistance of 0.031 ohm is drawn down so that its diameter is 5.0 mm. What does its resistance become? A. 0.85 ohm C. 0.93 ohm B. 0.78 ohm D. 0.81 ohm 9. EE Board Exam April 1995 A certain wire has a resistance R. The resistance of another wire identical with the first except for having twice its diameter is A. 4R C. 2R B. R/2 D. R/4 10. REE Board Exam October 1996 What is the size in square millimeter (mm 2) is the cable of 250 MCM size? A. 118.656 mm2 C. 112.565 mm2 B. 126.675 mm2 D. 132.348 mm2 11. REE Board Exam October 1998, September 2001 The resistance of a copper wire at 30°C is 50 ohms. If the temperature coefficient of copper at 0°C is 0.00427, what is the resistance at 100°C? A. 72.26 ohms C. 63.24 ohms

B. 54.25 ohms

D. 58.15 ohms

12. REE Board Exam March 1998 The resistance of a wire is 126.48 Ω at 100°C and 100 Ω at 30°C. Determine the temperature coefficient of copper at 0°C. A. 0.00427/°C C. 0.0256/°C B. 0.00615/°C D. 0.365/°C 13. EE Board Exam October 1991 Two heating elements which is 500 ohms and 250 ohms are connected in series with temperature coefficients of 0.001 and 0.003 ohms per °C, respectively at 20°C. Calculate the effective temperature coefficient of the combination. A. 0.00215 C. 0.00712 B. 0.00626 D. 0.00167 14. EE Board Exam October 1992 The insulation resistance of a kilometer of the cable having a diameter of 2 cm and an insulation thickness of 2 cm is 600 ohms. If the thickness of the insulation is increased to 3 cm, find the insulation resistance of the cable. A, 725 ohms C. 757 ohms B. 850 ohms D. 828 ohms 15. EE Board Exam April 1989 It is required that a loading of 3 kW be maintained in a heating element at an initial temperature of 20°C, a voltage of 220 V is necessary for the purpose. After the element has settled down to steady state, it is found that a voltage of 240 volts is necessary to maintain the 3 kW loading. The element resistance temperature coefficient is 0.0006 per degree centigrade at 20°C. Calculate the final temperature of the heating element. A. 345.43°C C. 336.84°C B. 326.42°C D. 318.48°C 16. REE Board Exam October 1999 How long must a current of 5 A pass through a 10 ohm resistor until a charge of 12000 coulomb passes through? A. 1 min C. 3 min B. 2 min D. 4 min

What is the power required to transfer 97,000 coulombs of charge through a potential rise of 50 volts in one hour? A. 0.5 kW C. 1.3 kW B. 0.9 kW D. 2.8 kW 18. REE Board Exam April 2001 A round wire has 250 MCM. Find its diameter in inches. A. ½ C. 0.16 B. ¼ D. 0.08 19. REE Board Exam September 2003 In the American wire gauge, as the number of gauge increases, the diameter of wire ____ A. increases B. decreases C. does not change D. become twice 20. REE Board Exam September 2003 In cgs system, what is the unit of emf where I is in abampere and P is in erg per second? A. millivolt C. abvolt B. kilovolt D. volt 21. REE Board Exam September 2002 One (1) kW is equal to ____ hp. A. 0.746 C. 550 B. 1.34 D. 1.5 22. REE Board Exam October 1998 Two copper conductors have equal length. The cross-sectional area of one conductor is three times that of the other. If the resistance of the conductor having smaller cross-sectional area is 20 Ω, what is the resistance of the other? A. 20/3 Ω C. 180 Ω B. 60 Ω D. 20/9 Ω 23. REE Board Exam October 2000 A copper bar has a length of 20 ft., width of 4 inches and thickness of 0.5 inch. If the resistivity of copper is 10.37 Ω-CM/ft, what is the resistance of the bar? A. 81.4 μΩ C. 814 μΩ B. 8.14 μΩ D. 0.814 μΩ 24. REE Board Exam April 2001

17. REE Board Exam October 1999

The resistance of the field winding of a DC machine is 0.25 Ω at 25°C. When operating at full-load, the temperature of the winding is 75°C. The temperature coefficient of resistance of copper is 0.00427 per °C at 0°C. Find the resistance of the field winding at full-load. A. 0.298 Ω C. 0.512 Ω B. 0.315 Ω D. 0.271 Ω

B. watt second

D. joule

32. ECE Board Exam November 1995 What composes all matter whether a liquid, solid or gas? A. electrons C. protons B. atoms D. neutrons

25. REE Board Exam October 2000 A coil of copper has resistance of 5.46 Ω at 75°C. What will be its resistance at 25°C? A. 4.58 Ω C. 5.02 Ω B. 4.84 Ω D. 4.35 Ω

33. ECE Board Exam November 2001 What is a physical combination of compounds or elements NOT chemically combined that can be separated by physical means? A. substance C. mixture B. atom D. molecule

26. REE Board Exam April 2001 A certain generator generates 1,500,000 joules per minute. What is the output in kW? A. 50 C. 25 B. 500 D. 125

34. ECE Board Exam April 1998 Determine the equivalent work of 166 wattsecond. A. 10 joules C. 16.6 joules B. 100 joules D. 166 joules

27. ECE BOARD NOV 2001 _____ is anything that has weight had occupies space. It may be solid, liquid or gas. A. Amalgam C. Matter B. Alloy D. Compound

35. ECE Board Exam November 2001 One of the following is the best conductor of electricity. A. Air C. Carbon B. Copper D. Silicon

28. ECE Board Exam April 2000 It is defined as anything that occupies space and has weight. A. atom C. molecule B. compound D. matter

36. ECE Board Exam November 1999 What is the basic unit for measuring current flow? A. coulomb C. volt B. ampere D. atomic weight

29. ECE Board Exam November 1999 The lightest kind of atom or element A. hydrogen C. titanium B. helium D. oxygen

37. ECE Board Exam November 1995 ______ has a unit of electron volt A. Energy C. Current B. Potential difference D. Charge

30. ECE Board Exam November 1998 In order to have a good conductor material, such material shall have _____ valence electrons. A. one C. more than ten B. five D. twenty one

38. ECE Board Exam November 2001 The motion of charged particles especially colloidal particles through a relative stationary liquid under the influence of an applied electric provided. A. hysteresis C. electrophoresis B. electrolysis D. electro analysis

31. ECE Board Exam November 1997 Electric power refers to _____ A. volt ampere C. volt coulomb

39. ECE Board Exam April 2001

What is a symbol that represents a quantity or a single object? A. unit C. item B. number D. base 40. ECE Board Exam April 2000 Determine which of the following has the least number of electrons found at the outer shell. A. semi-insulator C. semiconductor B. insulator D. conductor 41. ECE Board Exam April 2001 The term describes a material whose resistance remains relatively constant with changes in temperature A. positive temperature coefficient B. negative temperature coefficient C. neutral temperature coefficient D. zero temperature coefficient 42. ECE Board Exam November 1998 Resulting effect when electron is made to move A. dynamic electricity C. lines of force B. static electricity D. magnetic lines

A chemical combination of elements can be separated by chemical means but not by physical means. It is created by chemically combining two or more elements. A. molecules C. matter B. compound D. mixture 47. ECE Board Exam April 2000 A substance which cannot be reduced to a simpler substance by chemical means A. atom C. matter B. molecule D. element 48. ECE Board Exam November 2001 Calculate the equivalent power in watt of 100 joules per second. A. 1.66 watts C. 16.66 watts B. 100 watts D. 1,000 watts 49. ECE Board Exam April 2001 It is a neutral particle that has no electrical charge. A. atom C. electron B. proton D. neutron 50. ECE Board Exam November 1999 Which material has more free electrons? A. mica C. conductor B. insulator D. dielectric

43. ECE Board Exam November 1997 One of the following characteristics of a resistive material which do not change its resistive value with respect to time is its _____ A. fidelity C. stability B. sensitivity D. selectivity

51. ECE Board Exam November 2001 The new and preferred term for conductance or mho A. Siemens C. Seaman B. She-man D. ROM

44. ECE Board Exam November 2001 What do you call the element that conducts electricity very readily? A. semi-conductors C. insulators B. conductors D. dielectric

52. ECE Board Exam April 2001 Represents the current flow produced by one volt working across one ohm of resistance. A. resistance B. ampere C. voltage D. electromotive force

45. ECE Board Exam April 2001 Which of the following material is referred to as a medium whereby electrons can move easily from atom to atom? A. insulator C. mica B. dielectric D. conductor

53. ECE Board Exam November 1995 When an atom gains an additional _____, it results to a negative ion. A. atom C. proton B. neutron D. electron

46. ECE Board Exam November 2001

54. ECE Board Exam November 1999

The definite discrete amount of energy required to move an electron from a lower shell to higher shell. A. quantum B. positive energy C. negative energy D. quanta 55. ECE Board Exam November 1999 What will happen to an atom if an electron is either taken out or taken into the same atom? A. becomes a negative ion B. becomes an ion C. becomes a positive ion D. nothing will happen 56. ECE Board Exam April 1999 The energy in an electron that is called the energy of motion A. electromotive force B. kinematics C. kinetic energy D. potential energy 57. ECE Board Exam November 1996 Electric charge of neutron is the same as ______. A. atom C. current B. electron D. proton 58. ECE Board Exam April 1998 Ion is _____. A. free electron B. nucleus without protons C. proton D. an atom with unbalanced charges 59. ECE Board Exam November 1997 An insulating element or material has capability of _____. A. storing voltage B. preventing short circuit between two conducting wires C. conducting large current D. storing high current 60. ECE Board Exam April 1998 What is the value of a resistor with colors from left: Orange, Blue, Gold and Silver? A. 34 ohms + /-10%

B. 36 ohms +/-10% C. 3.4 ohms +/-10% D. 3.6 0hms +/-10% 61. ECE Board Exam April 2001 A three-terminal resistor with one or more sliding contacts which functions as an adjustable voltage divider A. Rheostat C. Potentiometer B. Bleeder resistor D. Voltage divider 62. ECE Board Exam November A resistor which is used to amount of current A. potentiometer C. B. bleeder resistor D.

2000 draw a fixed fixed resistor rheostat

63. ECE Board Exam November 2001 Find the value of a resistor with the following color codes: Orange, Yellow, Red, Red A. 34 k ohms +/-5% B. 3.4 ohms +/-2% C. 3.4 k ohms +/-10% D. 34 k ohms +/-20% 64. ECE Board Exam November 1996 Electric energy refers to ______. A. Joules divided by time C. Watt B. Volt-ampere D. Volt-coulomb 65. ECE Board Exam April 2001 What is the resistance of an open fuse circuit? A. at least 1000 ohms B. infinity C. zero D. 100 ohms at standard temperature 66. ECE Board Exam April 1998 When should a fuse be replaced with a higher rated unit? A. when the fuse of the original value is small in size B. when the original is not available C. never D. if it blows 67. ECE Board Exam November 2000 The ability to do work

A. energy B. kinetic

C. potential D. voltage

D. Gray, gray, black

68. ECE Board Exam November 2001 Which type of variable resistor should you use for controlling large amount of current? A. Potentiometer C. Variac B. Adjustable wirewound D. Rheostat

75. ECE Board Exam November 1998 If the bands on a resistor are yellow, violet, red and gold, what is the resistance value? A. 470 ohms 5% B. 470 ohms 10% C. 47000 ohms 5% D. 4700 ohms 5%

69. ECE Board Exam April 2000 What does the fourth loop of an electronic resistor color code represent? A. Multiplier B. Temperature C. First digit of the equivalent value D. Tolerance

76. ECE Board Exam November 1997 Rust in electrical (wire) connections will result to _____ A. Conductance C. Voltage B. Resistance D. Inductance

70. ECE Board Exam November 2000 Ten micro-microfarads is equivalent to _____ A. 100 picofarads B. 100 nanofarad C. 1000 milli microfarad D. 10.0 picofarads 71. ECE Board Exam November 1995 How much is the resistance of a germanium slag 10 cm long and cross sectional area of 1 square cm? A. 55 k ohms C. 550 k ohms B. 5.5 k ohms D. 550 ohms

77. ECE Board Exam November 1996 The area of a conductor whose diameter is 0.001 inch is equal to A. One micron C. One circular mil B. One angstrom D. One steradian 78. ECE Board Exam November 1995 _____ is the term used to express the amount of electrical energy in an electrostatic field. A. Joule C. Volt B. Coulomb D. Watt

72. ECE Board Exam November 2001 A variable resistor normally used as a voltage divider A. Carbon film resistor B. Potentiometer C. Adjustable resistor D. Metal film resistor

79. ECE Board Exam November 1995 Which of the following statement is correct? A. Potentiometer has two terminals B. Transistor has two terminals C. Typical power rating of a carboncomposition resistor ranged from 0.125 W to 2 W D. Open resistor has small resistance

73. ECE Board Exam April 2001 Determine the equivalent horse power of 2.611 kilowatts. A. 3.50 hp C. 2.25 hp B. 2.50 hp D. 1.50 hp

80. ECE Board Exam November 1996 _____ is one factor that does not affect resistance. A. Resistivity C. Length B. Cross sectional area D. Mass

74. ECE Board Exam November 2000 Find the lowest resistance value of the following resistors. A. White, black, black B. Violet, gray, yellow, silver C. Red, black, gold

81. ECE Board Exam November 1998 What is the value of a resistor having the following colored bands: Yellow-Gray-RedSilver? A. 4800 ohms ±10%

B. 480 ohms ±10% C. 3800 ohms ±1% D. 4.8 ohms ±1% 82. ECE Board Exam November 1997 Find the value of resistor with the following color codes; Brown, White, Orange, Red A. 190 ohms 10% B. 19 k ohms 2% C. 1.9 k ohms 10% D. 19 k ohms 20% 83. ECE Board Exam November 1998 Resistor with colored bands in the body A. Adjustable resistor B. Wire-wound resistor C. Variable resistor D. Carbon composition resistor 84. ECE Board Exam November 1998 If the bands on a resistor are red, red, orange and silver, what is the resistance value? A. 220 ohms 5% B. 223 0hms 10% C. 22,000 ohms 10% D. 2200 ohms 20% 85. ECE Board Exam November 1997 What does the second strip of an electronic resistor color code represent? A. Tolerance B. Second digit of the value C. Temperature D. Multiplier 86. ECE Board Exam November 2000 The energy in an electron that is called the energy of position A. Kinetic energy B. Kinematics C. Electromotive force D. Potential energy

What happens to the resistance of a conductor wire when its temperature is lowered? A. Decreased C. Zero B. Steady D. Increased 89. ECE Board Exam April 1998 Which of the following does not refer to electric energy? A. Joule C. Volt coulomb B. Watt second D. Volt ampere 90. ECE Board Exam March 1996 Which of the following statement is incorrect? A. open transistor has three (3) terminals B. transistors have three (3) terminals C. typical power rating of carboncomposition resistor ranged 0.001 W to 0.1 W D. potentiometer has three (3) terminals 91. ECE Board Exam November 1997 Term used in electronic measuring device when a metal increases resistance due to heat produced by current flowing through them. A. positive resistance coefficient B. positive temperature coefficient C. negative temperature coefficient D. negative resistance coefficient 92. A 1 km cable consists of 12 identical strands of aluminum each 3 mm in diameter. What is the resistance of the cable? A. 0.34 ohm C. 0.44 ohm B. 0.54 ohm D. 0.24 ohm 93. A piece of wire has a resistance of 0.5 ohm. The length is doubled and the area is increased four times. What is its resistance? A. 0.75 ohm C. 0.25 ohm B. 0.50 ohm D. 1 ohm

87. ECE Board Exam April 1999 If an electronic resistor does not have the fourth color strip it means it has a tolerance of _____. A. 5% C. 10% B. 20% D. 1%

94. Copper wire of certain length and resistance is drawn out to four times its length without change in volume. What is the resistance of the bar? A. unchanged C. 16R B. R/16 D. 4R

88. ECE Board Exam April 1998

95. Current is simply _____.

A. Flow of electrons B. Flow of protons

C. Radiation D. Emission

96. The resistance of a coil of wire is 1 kΩ at 20°C. If the coil is immersed into oil, the resistance falls to 880 Ω. If the wire has a temperature coefficient of 0.006 at 20°C, how much is the temperature of the liquid? A. 0°C C. 17.6°C B. -20°C D. none of these 97. The copper field coils of a motor was measured at 21°C and found to have a resistance of 68 Ω. After the motor has run for a given time, the resistance is found to be 96 Ω. What is the hot temperature of the winding? A. 106.36°C C. 103.66°C B. 166.30°C D. none of these 98. A wire has a resistance of 30 Ω at 20°C. What will its resistance be at 60°C? Assume the temperature coefficient of resistance to be 0.000385 at 20°C. A. 34.26 Ω C. 32.46 Ω B. 36.42 Ω D. none of these 99. Determine the length of a copper wire (ρ = 10.37 Ω-CM/ft) where diameter is 0.30 inch and resistance of 0.5 Ω at 20°C. A. 4,339 ft C. 6,125 ft B. 5.225 ft D. none of these 100. An electric water heater has a rating of 1 kW, 230 V. The coil used as the heating element is 10 m long and has a resistivity of 1.724 x 10-6 ohm-cm. Determine the required diameter of the wire in mils. A. 2.43 mils C. 3.21 mils B. 2.52 mils D. 1.35 mils 101. A certain wire 20 ft long and 100 circu...