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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 L 2 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.

B.

1895 ohms

1825 ohms

C.

D.

1792 ohms

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 mm 2 C. 112.565 mm 2 B. 126.675 mm 2 D. 132.348 mm 2

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

What is the power required to transfer 97,000 coulombs of charge through a potential rise of 50 volts in one hour?

 The resistance of a wire is 126.48 Ω at 100°C A. 0.5 kW C. 1.3 kW and 100 Ω at 30°C. Determine the temperature coefficient of copper at 0°C. B. 0.9 kW D. 2.8 kW A. 0.00427/°C C. 0.0256/°C 18. REE Board Exam April 2001 B. 0.00615/°C D. 0.365/°C A round wire has 250 MCM. Find its diameter in inches. 13. EE Board Exam October 1991 A. ½ C. 0.16 B. ¼ D. 0.08 Two heating elements which is 500 ohms and 250 ohms are connected in series with temperature coefficients of 0.001 and 0.003 19. REE Board Exam September 2003

ohms per °C, respectively at 20°C. Calculate the effective temperature coefficient of the

In the American wire gauge, as the number

of gauge increases, the diameter of wire

 combination. A. increases A. 0.00215 C. 0.00712 B. decreases B. 0.00626 D. 0.00167 C. does not change

D. become twice

 14. EE Board Exam October 1992 The insulation resistance of a kilometer of 20. REE Board Exam September 2003 the cable having a diameter of 2 cm and an In cgs system, what is the unit of emf where I insulation thickness of 2 cm is 600 ohms. If is in abampere and P is in erg per second? the thickness of the insulation is increased to A. millivolt C. abvolt 3 cm, find the insulation resistance of the B. kilovolt D. volt

cable.

 A, 725 ohms C. 757 ohms 21. REE Board Exam September 2002 B. 850 ohms D. 828 ohms One (1) kW is equal to hp. A. 0.746 C. 550 B. 1.34 D. 1.5 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 22. REE Board Exam October 1998 Two copper conductors have equal length.
 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 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? per degree centigrade at 20°C. Calculate the A. 20/3 Ω C. 180 Ω final temperature of the heating element. B. 60 Ω D. 20/9 Ω
 A. 345.43°C C. 336.84°C B. 326.42°C D. 318.48°C 23. REE Board Exam October 2000

16. REE Board Exam October 1999

A copper bar has a length of 20 ft., width of 4

inches and thickness of 0.5 inch. If the

 How long must a current of 5 A pass through resistivity of copper is 10.37 Ω-CM/ft, what is the resistance of the bar? a 10 ohm resistor until a charge of 12000 coulomb passes through? A. 81.4 μΩ C. 814 μΩ A. 1 min C. 3 min B. 8.14 μΩ D. 0.814 μΩ B. 2 min D. 4 min

24. REE Board Exam April 2001

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

B.

watt second

D.

joule

32. ECE Board Exam November 1995

What composes all matter whether a liquid, solid or gas?

 0°C. Find the resistance of the field winding A. electrons C. protons at full-load. B. atoms D. neutrons
 A. 0.298 Ω C. 0.512 Ω B. 0.315 Ω D. 0.271 Ω 33. ECE Board Exam November 2001 What is a physical combination of

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?

compounds or elements NOT chemically combined that can be separated by physical means?

 A. 4.58 Ω C. 5.02 Ω A. substance C. mixture B. 4.84 Ω D. 4.35 Ω B. atom D. molecule

26. REE Board Exam April 2001

A certain

joules per minute. What is the output in kW?

A.

generator

generates

C.

D.

25

125

1,500,000

50

500

B.

 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 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 29. ECE Board Exam November 1999 The lightest kind of atom or element A. hydrogen C. titanium B. helium D. oxygen 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 31. ECE Board Exam November 1997 Electric power refers to A. volt ampere C. volt coulomb

34. ECE Board Exam April 1998 Determine the equivalent work of 166 watt-

second.

A.

B.

10 joules

100 joules

C.

D.

16.6 joules

166 joules

35. ECE Board Exam November 2001

One of the following is the best conductor of

electricity.

 A. Air C. Carbon B. Copper D. Silicon

36. ECE Board Exam November 1999 What is the basic unit for measuring current

flow?

A.

B.

weight

coulomb

ampere

C.

D.

volt

atomic

37. ECE Board Exam November 1995 has a unit of electron volt

 A. Energy C. Current B. Potential difference D. Charge

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

39. ECE Board Exam April 2001

 What is a symbol that represents a quantity or a single object? A chemical combination of elements can be A. unit C. item separated by chemical means but not by physical means. It is created by chemically B. number D. base combining two or more elements.
 A. molecules C. matter 40. ECE Board Exam April 2000 B. compound D. mixture Determine which of the following has the least number of electrons found at the outer 47. ECE Board Exam April 2000

shell.

A substance which cannot be reduced to a

 A. semi-insulator C. simpler substance by chemical means semiconductor A. atom C. matter B. insulator D. conductor B. molecule D. element
 41. ECE Board Exam April 2001 The term describes a material whose resistance remains relatively constant with 48. ECE Board Exam November 2001 Calculate the equivalent power in watt of 100 joules per second. changes in temperature A. 1.66 watts C. 16.66 watts A. positive temperature coefficient B. 100 watts D. 1,000 watts

B. negative temperature coefficient

C. neutral temperature coefficient

D. zero temperature coefficient

49. ECE Board Exam April 2001

It is a neutral particle that has no electrical

charge.

 42. ECE Board Exam November 1998 A. atom C. electron Resulting effect when electron is made to move B. proton D. neutron
 A. dynamic electricity C. lines of force 50. ECE Board Exam November 1999 B. static electricity D. magnetic Which material has more free electrons?
 lines 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

51. ECE Board Exam November 2001

The new and preferred term for conductance

or mho

 A. Siemens C. Seaman A. fidelity C. stability B. She-man D. ROM B. sensitivity D. selectivity

44. ECE Board Exam November 2001 What do you call the element that conducts electricity very readily?

52. ECE Board Exam April 2001

Represents the current flow produced by one volt working across one ohm of resistance.

A. resistance

 A. semi-conductors C. insulators B. ampere B. conductors D. dielectric C. voltage

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?

D. electromotive force

53. ECE Board Exam November 1995 When an atom gains an additional results to a negative ion.

, it

 A. insulator C. mica A. atom C. proton B. dielectric D. conductor B. neutron D. electron

46. ECE Board Exam November 2001

54. ECE Board Exam November 1999

The

required to move an electron from a lower shell to higher shell.

A. quantum

B. positive energy

C. negative energy

D. quanta

discrete amount of energy

definite

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

 55. ECE Board Exam November 1999 A. Rheostat C. What will happen to an atom if an electron is Potentiometer either taken out or taken into the same B. Bleeder resistor D. Voltage atom? divider

A. becomes a negative ion

B. becomes an ion

C. becomes a positive ion

D. nothing will happen

62. ECE Board Exam November 2000 A resistor which is used to draw a fixed amount of current

 A. potentiometer C. fixed resistor 56. ECE Board Exam April 1999 B. bleeder resistor D. rheostat

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

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%

 A. atom C. current 64. ECE Board Exam November 1996 Electric energy refers to B. electron D. proton A. Joules divided by time C. Watt

58. ECE Board Exam April 1998 Ion is

A.

B. nucleus without protons

C. proton

D. an atom with unbalanced charges

free electron

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. Volt-ampere D. Volt-coulomb

65. ECE Board Exam April 2001

What

circuit?

is

the

resistance

of

an

open

fuse

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 C. potential D. Gray, gray, black B. kinetic D. voltage 75. ECE Board Exam November 1998 68. ECE Board Exam November 2001 Which type of variable resistor should you If the bands on a resistor are yellow, violet, red and gold, what is the resistance value? use for controlling large amount of current? A. 470 ohms 5% A. Potentiometer C. Variac B. 470 ohms 10% B. Adjustable wirewound D. Rheostat 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? 76. ECE Board Exam November 1997 Rust in electrical (wire) connections will result A. Multiplier to B. Temperature A. Conductance C. Voltage C. First digit of the equivalent value B. Resistance D. Inductance D. Tolerance 77. ECE Board Exam November 1996 70. ECE Board Exam November 2000 The area of a conductor whose diameter is Ten micro-microfarads is equivalent to 0.001 inch is equal to A. 100 picofarads A. One micron C. One circular B. 100 nanofarad mil C. 1000 milli microfarad B. One angstrom D. One

71. ECE Board Exam November 1995 How much is the resistance of a germanium

78. ECE Board Exam November 1995 is the term used to express the amount

 slag 10 cm long and cross sectional area of 1 of electrical energy in an electrostatic field. square cm? A. Joule C. Volt A. 55 k ohms C. 550 k ohms B. Coulomb D. Watt B. 5.5 k ohms D. 550 ohms

72. ECE Board Exam November 2001

A variable resistor normally used as a voltage divider

A. Carbon film resistor

B. Potentiometer

D. Metal film resistor

73. ECE Board Exam April 2001 Determine the equivalent horse power of 2.611 kilowatts.

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 carbon- composition resistor ranged from 0.125 W to 2 W

D. Open resistor has small resistance

80. ECE Board Exam November 1996

is

resistance.

one

factor

that

does

not

affect

 A. 3.50 hp C. 2.25 hp A. Resistivity C. Length B. 2.50 hp D. 1.50 hp B. Cross sectional area D. Mass

74. ECE Board Exam November 2000

value

resistance

following resistors.

A. White, black, black

B. Violet, gray, yellow, silver

C. Red, black, gold

Find

the

lowest

of

the

81. ECE Board Exam November 1998 What is the value of a resistor having the following colored bands: Yellow-Gray-Red- Silver?

A. 4800 ohms ±10%

B. 480 ohms ±10%

What

happens

to

the

resistance

of

a

 C. 3800 ohms ±1% conductor wire when its temperature is D. 4.8 ohms ±1% lowered? A. Decreased C. Zero 82. ECE Board Exam November 1997 B. Steady D. Increased

Find the value of resistor with the following color codes; Brown, White, Orange, Red

A. 190 ohms 10%

B. 19 k ohms 2%

89. ECE Board Exam April 1998 Which of the following does not refer to electric energy?

 C. 1.9 k ohms 10% A. Joule C. Volt coulomb D. 19 k ohms 20% B. Watt second D. Volt ampere

83. ECE Board Exam November 1998

Resistor with colored bands in the body

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

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 carbon- composition 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 86. ECE Board Exam November 2000 A. Kinetic energy B. 0.54 ohm D. 0.24 ohm The energy in an electron that is called the energy of position 93. A piece of wire has a resistance of 0.5 ohm. The length is doubled and the area is

B. Kinematics

increased four times. What is its resistance?

 C. Electromotive force A. 0.75 ohm C. 0.25 ohm D. Potential energy 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.

B.

5%

20%

C.

D.

10%

1%

88. ECE Board Exam April 1998

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

95. Current is simply

 A. Flow of electrons C. Radiation 102. How many B. Flow of protons D. Emission circular mils does a round copper rod of 0.25 inch diameter have?
 96. The resistance of a coil of wire is 1 kΩ at A. 196,000 C. 1,963,500 20°C. If the coil is immersed into oil, the B. 62,500 D. 49,000 resistance falls to 880 Ω. If the wire has a temperature coefficient of 0.006 at 20°C, 103. A substance how much is the temperature of the liquid? whose molecules consist of the same kind of A. 0°C C. 17.6°C atoms is called B. -20°C D. none of these A. mixture

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

is the hot temperature of the

96 Ω. What 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.

B.

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.

B.

100.

4,339 ft

5.225 ft

C.

D.

6,125 ft none of these

2.43 mils

2.52 mils

C.

D.

3.21 mils

1.35 mils

101.

A certain wire 20

a

100 circular

resistance of 1.6 . What is its resistivity?

A. 10.3 ohm-CM/ft

B. 2.2 ohm-CM/ft

ft

long

and

mil

area

has

C. 8 ohm-CM/ft

D. 15.2 ohm-CM/ft

B. element

C. compound

D. none of the above

 104. The diameter of the atom is about A. 10 -10 m C. 10 -2 m B. 10 -8 m D. 10 -15 m 105. The number of compounds available in nature is A. 105 C. 1000 B. 300 D. unlimited 106. The mass of a

proton is

A. equal to

B. less than

D. 200 times

the mass of an electron.

 107. The maximum number of electrons that can be accommodated in the last orbit is A. 4 C. 18 B. 8 D. 2 108. The electrons in the last orbit of an atom are called electrons. A. free C. valence B. bound D. thermionic

109.

If the number of

valence electrons of an atom is less than 4, the substance is usually

A. a conductor

B. an insulator

C. a semiconductor

D. none of the above

 110. If the number of 117. EMF has the unit valence electrons of an atom is more than 4, of the substance is usually A. power C. charge A. a semiconductor B. energy D. none of these B. a conductor C. an insulator 118. Potential

D. none of the above

111.

If the number of

valence electrons of an atom is exactly 4, the

substance is usually

A. a semiconductor

B. an insulator

C. a conductor

D. a semiconductor

112.

The

number

of

valence electrons of an atom is less than 4. The substance will be probably

A. a metal

B. a non-metal

C. an insulator

D. a semiconductor

113.

charge

electrons.

A.

B.

is

equal

628 x 10 16 6.28 x 10 16

114.

has

temperature.

A.

B.

20 x 10 10

200

to

the

One

coulomb

charge

on

C.

D.

62.8 x 10 16 0.628 x 10 16

of

One cc of copper free electrons at room

C.

D.

8.5 x 10 22 3 x 10 5

115.

a wire is the flow of

A. free electrons

B. bound electrons

C. valence electrons

D. atoms

116.

Electric current in

EMF in a circuit is

A. cause current to flow

B. maintains potential difference

difference has the unit of

.

 A. charge B. power C. energy D. none of the above 119. The resistance of a material is its area of cross-section. A. directly proportional to B. inversely proportional to C. independent of D. none of the above 120. If the length and

area of cross-section of a wire are doubled up, then its resistance

 A. becomes four times B. remains unchanged C. becomes sixteen times D. none of the above 121. A length of wire

has a resistance of 6 ohms. The resistance of

a wire of the same material three times as

long and twice the cross-sectional area will be

 A. 36 ohms C. 9 ohms B. 12 ohms D. 1 ohm

122.

specific resistance is

The

SI

unit

of

 A. mho C. ohm-m 2 B. ohm-m D. ohm-cm
 123. The specific resistance of a conductor with rise in temperature. A. increases B. decreases C. remains unchanged D. none of the above 124. The SI unit of
 C. increases the circuit resistance conductivity is D. none of these A. ohm-m C. mho-m B. ohm/m D. mho/m
 125. The SI unit of D. none of the above conductance is A. mho C. ohm-m 132. Eureka has B. ohm D. ohm-cm temperature coefficient of resistance. A. positive 126. The resistance of B. negative a material 2 m long and 2 m 2 in cross- C. almost zero sectional area is 1.6 x 10 -8 Ω. Its specific D. none of the above resistance will be
 A. 3.2 x 10 -8 ohm-m B. 6.4 x 10 -8 ohm-m C. 1.6 x 10 -8 ohm-m D. 0.16 x 10 -8 ohm-m 127. Conductors have temperature coefficient of resistance. A. positive B. negative C. zero D. none of the above 128. Semiconductors have temperature coefficient of resistance. A. negative B. positive C. zero D. none of the above 129. The value of α

(i.e. temperature coefficient of resistance) depends upon

A. length of the material

B. cross-sectional area of the material

C. volume of the material

D. nature of the material and

 temperature 130. The temperature

coefficient of resistance of a conductor with rise in temperature.

A. increases

B. decreases

C. remains unchanged

D. none of the above

131.

Insulators

have

temperature coefficient of resistance.

A. zero

B. positive

133.

shows

the temperature/resistance graph of a conductor. The value of α 0 is

Fig.

1.1

 A. 0.005/°C C. 0.1/°C B. 0.004/°C D. 0.4/°C 134. Referring to Fig. 1.1, the value of the α 50 will be A. 0.005/°C C. 0.1/°C B. 0.004/°C D. 0.4/°C 135. Referring to Fig. 1.2, the value of α 0 is A. 1/30 per °C B. 1/40 per °C C. 1/1200 per °C D. none of the above 136. Referring to Fig.

1.2, the value of R 40 will be

A.

B.

137.

70 ohms

40 ohms

C.

D.

35 ohms

50 ohms

Referring

to

1.2, the value of α 40 will be

Fig.

141.

Two wires A and

B have the same cross-section and are made

of the same material, R A = 600 Ω and R B =

100 Ω. The number of times A is longer than

B is

 A. 6 C. 4 B. 2 D. 5 142. A coil has a resistance of 100 Ω at 90°C. At 100°C, its resistance is 101 Ω. The temperature coefficient of wire at 90°C is A. 0.01 C. 0.0001 B. 0.1 D. 0.001
 143. Which of the following material has nearly zero

temperature-coefficient of resistance?

 A. carbon C. copper B. porcelain D. manganin

144.

following

material

Which

has

a

of

negative

the

 A. 1/30 per °C C. 1/50 per °C temperature coefficient of resistance? B. 1/70 per °C D. 1/1200 per A. brass C. aluminum °C B. copper D. carbon 138. The value of α 0 of 145. A cylindrical wire

a conductor is 1/236 per °C. The value of α 18 will be

A. 1/218 per °C

B. 1/272 per °C

1 m in length, has a resistance of 100 .

What would be the resistance of a wire made from the same material both the length and the cross-sectional area are doubled?

 C. 1/254 per °C A. 200 C. 100 D. none of the above B. 400 D. 50

139.

The value of

α 50

146.

Carbon

 of a conductor is 1/230 per °C. The value of composition resistors are most popular α 0 will be because they

A. 1/180 per °C

1/280 per °C

C. 1/250 per °C

B.

D. none of the above

140.

A

good

electric

conductor is one that

A. has low conductance

B. is always made of copper wire

C. produces a minimum voltage drop

D. has few free electrons

A. cost the least

are smaller

B.

D. do not produce electric noise

147.

A unique feature

of a wire-wound resistor is its

 A. lower power rating C. high stability B. low cost D. small size 148. A coil has a

resistance of 100 ohms at 90 ° C. At 100°C, its

 resistance is 101 ohms. What is the A. 0.217 siemens C. 4.52 siemens temperature coefficient of the wire at 90 ° C? B. 3.41 siemens D. 0.562
 A. 0.01 C. 0.0001 siemens B. 0.1 D. 0.001

155. REE Board Exam October 1997

 149. What is the unit A 5-ohm resistance is connected in parallel for charge (Q)? with a 10-ohm resistance. Another set, a 6- A. Farad C. Siemens ohm and an 8-ohm resistances are also B. Joule D. Coulomb connected in parallel. The two sets are connected in series. What is the equivalent 150. The charge resistance?
 delivered by a constant voltage source is A. 6.76 ohm C. 14.4 ohms shown. Determine the current supplied by B. 9.25 ohm D. 21.2 ohms

the source at (a) t = 1 s (b) t = 3 s.

 A. 5 ma, -3.33 ma C. –3.33 ma, 5 ma B. 5 ma, 3.33 ma D. 3.33 ma, 5 ma

B. OHM’S LAW AND ELECTRIC CIRCUITS

151. REE Board Exam October 1998

The resistance of 120 meters of wire is 12 ohms. What is its conductance?

 A. 0.0521 siemens C. 6 siemens B. 0.0833 siemens D. 12 siemens

152. EE April 1981, October 1984

Two (2) 115-V incandescent lamps A and B are connected in series across a 230-V

source. If lamp A is rated 75 watts and lamp B is rated 50 watts, determine the current drawn by the series connection.

A.

B.

0.52 A

0.64 A

C.

D.

0.48 A

0.57 A

153. REE Board Exam March 1998

Three resistors of 10, 15 and 20 ohms each

the

are

equivalent resistance?

A.

B.

connected

45 ohms

17.2 ohms

in

parallel.

C.

D.

What

is

0.22 ohm

4.62 ohms

154. REE Board Exam March 1998

Three resistors of 10, 15 and 20 ohms each are connected in parallel. What is the total conductance?

156. REE Board Exam March 1998

Two resistances of 10 and 15 ohms each respectively are connected in parallel. The two are then connected in series with a 5- ohm resistance. What is the equivalent resistance?

 A. 11 ohms C. 10 ohms B. 12 ohms D. 9 ohms

157. REE Board Exam October 1997

A 10-ohm and a 20-ohm resistance are connected in parallel. Another resistance of

5-ohm is connected in series with the two. If the supply voltage is 48 volts, what is the current through the 10-ohm resistor?

 A. 3.21 A C. 4.02 A B. 2.74 A D. 5.72 A

158. REE Board Exam March 1998

Two resistances of 10 and 15 ohms, each respectively are connected in parallel. The two are then connected in series with a 5-

ohm resistance. It is then connected across a

 12-V battery, what are the current and power? A. 1.2 A, 17.28 W C. 1.09 A, 13.1 W B. 0.96 A, 11.52 W D. 1.5 A, 20.25 W 159. REE Board Exam September 2001

Three resistors 10-Ω, 15-Ω and 20-Ω are connected in series across a 48-V source.

What is the voltage across the 15-Ω resistor?

 A. 20 V C. 24 V B. 16 V D. 12 V

160. REE Board Exam September 2001

The theory of Ohm’s law is applied in a

 Three resistors 10-Ω, 15-Ω and 20-Ω are circuit. connected in parallel. What is the total A. linear C. trivalent resistance? B. exponential D. unilateral
 A. 3.56 Ω C. 0.217 Ω B. 4.62 Ω D. 45 Ω 167. ECE Board Exam April 2000 Refers to the most important components in controlling flow of electrons 161. REE Board Exam September 2000 A. voltage, electromotive force and current

Two 10-Ω resistances are connected in

parallel. The two are then connected in series with a 5-Ω resistance. It is then connected across a 24-volt battery; find the voltage across the 5-Ω resistor.

B. reactance, current and resistance

C. conductance, resistance and reactance

D. voltage, resistance and current

168. ECE Board Exam November 1999

 A. 12 volts C. 9 volts Which of the following is not a valid B. 24 volts D. 15 volts expression of ohm’s law? A. E = IR C. R = E/I 162. REE Board Exam April 1997 B. R = PI D. I = E/R A circuit consists of three resistors rated 3-Ω,

4-Ω and 5-Ω connected in parallel. If the

169. ECE Board Exam November 2000

 circuit is connected to a battery which has an internal resistance of 0.2-Ω, what would be the current through the 4-Ω resistor? A simple electronic equipment which takes a 2 amperes current from a power source has a A. 2.04 A C. 2.4 A total load resistance of 100 ohms. How much power does it use? B. 4.8 A D. 3.0 A A. 200 watts C. 400 watts B. 100 watts D. 50 watts

163. REE Board Exam September 2000 How many abvolts in 1 volt?

170. ECE Board Exam November 1996

 A. 10 8 abvolts C. 1 abvolt What do you expect when you use the two 20 A. Provide lighter current B. 10 -8 abvolts D. 10 abvolt kohms, 1 watt resistor in parallel instead of 164. REE Board Exam September 2003 one 10 kohms, 1 watt? A total current of 60 A is divided among 3 B. Provide wider tolerance

parallel branches having resistances of 10 Ω,

Ω and 12 Ω, respectively. What is the

current that flows through the branch with 10

6

Ω resistance?

C. Provide more power

D. Provide less power

171. ECE Board Exam November 1999

 A. 17.1 A C. 14.3 A The total resistance of a two similar wire B. 28.6 A D. 42.9 A conductors connected in parallel is

165. REE Board Exam October 2000

Two 10-ohm parallel resistors are connected

in series with a 5-ohm resistor. The

combination is then connected across a 24 volts battery. Find the voltage drop across the 5-ohm resistor.

A.

B.

6 V

18 V

C.

D.

12 V

20 V

166. ECE Board Exam November 1998

A. same resistance of one wire

B. double the resistance of one wire

C. one half the resistance of one wire

D. resistance of one wire multiplied by 4

172. ECE Board Exam March 1996

When you increase the resistance in a circuit, the flow of electrons will

 A. be constant C. be stopped B. flow faster D. be decreased

173. ECE Board Exam April 2001

Which of the following allows more current if applied to the same voltage?

A series circuit in which desired portions of the source voltage may be tapped off for use

 A. 0.002 siemen C. 0.004 siemen equipment. B. 25 ohms D. 2.5 ohms A. Voltage trap B. Voltage selector 174. ECE Board Exam April 1998 C. Voltage divider Ohm’s law refers to D. Dividing network A. power is directly proportional to both voltage squared and the resistance 180. ECE Board Exam April 1998

B. power is directly proportional to the resistance and inversely as the current squared

C. current varies directly as the voltage and inversely as the resistance

D. current is directly proportional to both voltage and resistance

175. ECE Board Exam November 2000

A circuit which a break exists in the complete conduction pathway

A.

B.

Open circuit

Short circuit

C.

D.

Close circuit

Circuit

176. ECE Board Exam November 1997

How much is the equivalent power in watts can a 3 horse power provide?

A.

B.

3000 watts

248.66 watts

C.

D.

1492 watts

2238 watts

177. ECE Board Exam March 1996

The current needed to operate a soldering iron which has a rating of 600 watts at 110 volts is

A.

B.

18,200 A

0.182 A

C.

D.

66,000 A

5.455 A

178. ECE Board Exam November 1997

Find the power across the resistor of 5 ohms

internal

resistance of 3 ohms and a constant emf of 4

volts.

delivered

from

a

battery

of

an

A.

B.

120 watts

100 watts

C.

D.

60 watts

1.25 watts

179. ECE Board Exam April 2000

An electronic device draws 300 watts from its

source. Find effective

24

resistance.

volt

power

 A. 1.25 Ω C. 19.20 Ω B. 1.92 Ω
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