MCQs in ELECTRICITY AND MAGNETISM

122. One oersted (Oe) is equivalent to ______ Gb/cm. A. 1 B. 10 C. 100 D. 1000

A. 1

128. A good conductor has how many valence electrons? A. 1 B. 4 C. 2 D. 8

A. 1

121. How much is the flux in Weber are there in a magnetic flux of 2000 lines A. 2 x 10^-5 B. 2 x 10^-3 C. 2 x 10^5 D. 2 x 10^3

A. 2 x 10^-5

99. Germanium atom has __ protons and __ electrons. A. 32, 32 B. 32, 42 C. 42, 32 D. 34, 34

A. 32, 32

141. How many electrons are needed in the valence orbit to give a material's stability? A. 8 B. 4 C. 6 D. 5

A. 8

1. What is the diameter of an atom? A. About 10^-10 m B. About 10^-10 cm C. About 10^-10 mm D. About 10^-10 µm

A. About 10^-10 m

64. The air space between poles of magnets A. Air gap B. Free space C. Vacuum D. Atmosphere

A. Air gap

105. A commercial alloy of aluminum nickel, and iron with cobalt, copper and titanium added to produce about 12 grades. A. Alnico B. Brass C. Aluminum D. Constantan

A. Alnico

92. The tiniest element of matter A. Atom B. Proton C. Electron D. Neutron

A. Atom

73. The magnetic field of a magnetized iron bar when strongly heated A. Becomes weaker B. Becomes stronger C. Reverses in direction D. is unchanged

A. Becomes weaker

52. Permeance is analogous to A. Conductance B. Reluctance C. Admittance D. Resistance

A. Conductance

127. Which of the following has the least number of valence electrons? A. Conductor B. Semiconductor C. Insulator D. Semi- insulator

A. Conductor

86. A magnetic material losses its ferromagnetic properties at a point called A. Curie temperature B. Inferred absolute temperature C. Room temperature D. Absolute temperature

A. Curie temperature

76. The emf produced in a wire by its motion across a magnetic field does not depend upon the A. Diameter of the wire B. Length of the wire C. Orientation of the wire D. Flux density of the field

A. Diameter of the wire

42. The process by which an emf and hence current is generated or induced in a conductor when there is a change in the magnetic flux linking the conductor is called A. Electromagnetic induction B. Mutual induction C. Faraday's law D. Electromagnetic interference

A. Electromagnetic induction

130. A negative ion results when an atom gains an additional A. Electron B. Proton C. Neutron D. Atom

A. Electron

124. An electron- volt (eV) is a unit of A. Energy B. Potential difference C. Charge D. Momentum

A. Energy

34. Lenz's law is the consequence of the law of conservation of A. Energy B. Charge C. Field lines D. Momentum

A. Energy

63. Refers to the non- metallic materials that have the ferromagnetic properties of iron. A. Ferrites B. Ferromagnetic C. Diamagnetic D. Paramagnetic

A. Ferrites

110. Which of the following electric quantities is vector in character? A. Field B. Charge C. Energy D. Potential Difference

A. Field

62. Refers to the magnetic lines A. Flux B. Hysteresis C. Current D. Magnetomotive force

A. Flux

115. What is the cgs unit of magnetomotive force? A. Gilbert B. Ampere- turn C. Maxwell D. Weber

A. Gilbert

18. Who discovered the most important electrical effects which is the magnetic effect? A. Hans Christian Oersted B. Sir Charles Wheatstone C. Georg Ohm D. James Clerk Maxwell

A. Hans Christian Oersted

31. Who discovered superconductivity in 1911? A. Kamerlingh Onnes B. Alex Muller C. Geory Bednorz D. Charles Coulomb

A. Kamerlingh Onnes

4. The net electrical charge in an isolated system remains constant. This is known as A. Law of conservation of charge B. Coulomb's first law C. Coulomb's second law D. Law of conservation of energy

A. Law of conservation of charge

80. Steel is hard to magnetize because of its A. Low permeability B. High permeability C. High density D. High retentivity

A. Low permeability

11. The space outside the magnet where its pole have a force of attraction or repulsion on a magnetic pole is called A. Magnetic field B. Electric field C. Electromagnetic field D. Free Space Field

A. Magnetic field

59. The force acting on a unit n- pole placed at that point is called A. Magnetic field intensity B. Electric field intensity C. Electromagnetic field intensity D. Intensity magnetization

A. Magnetic field intensity

47. The total number of magnetic lines of force in a magnetic field is called A. Magnetic flux B. Magnetic flux density C. Magnetic flux intensity D. Magnetic potential

A. Magnetic flux

33. The point in a magnet where the intensity of magnetic lines of force is maximum A. Magnetic pole B. South pole C. North pole D. Unit pole

A. Magnetic pole

5. The point in a magnet where the intensity of magnetic lines of force is maximum A. Magnetic pole B. South pole C. North pole D. Unit pole

A. Magnetic pole

8. The phenomenon by which a subtracts pieces of iron A. Magnetism B. Electromagnetism C. Naturalism D. Materialism

A. Magnetism

36. Who demonstrated the theory of electromagnetic induction in 1831? A. Michael Faraday B. Andre Ampere C. James Clerk Maxwell D. Charles Coulomb

A. Michael Faraday

37. Who discovered that a current-carrying conductor would move when placed in a magnetic field? A. Michael Faraday B. Andre Ampere C. Hans Christian Oersted D. Gustav Robert Kirchhoff

A. Michael Faraday

25. The magnetic potential in a magnetic circuit can be measured in terms of A. Mmf B. Emf C. Farad D. Coulomb

A. Mmf

107. The physical motion resulting from the forces of magnetic fields is called A. Motor action B. Rotation C. Repulsion D. Torque action

A. Motor action

43. The emf induced in a coil due to the changing current of another neighboring coil is called A. Mutually induced emf B. Self induced emf C. Statically induced emf D. Dynamically induced emf

A. Mutually induced emf

75. A current if flowing east along a power line. If the earth's field is neglected, the direction of the magnetic field below it is A. North B. South C. East D. West

A. North

13. Materials whose permeabilities are slightly greater than that of free space A. Paramagnetic B. Non- magnetic C. Ferromagnetic D. Diamagnetic

A. Paramagnetic

103. An alloy of 22 percent iron and 78 per cent nickel. A. Permalloy B. Alnico C. Constantan D. Manganin

A. Permalloy

150. One of the common application of an air- cored choke. A. Radio frequency B. Audio frequency C. Power supply D. Power transformer

A. Radio frequency

51. The ratio of the permeability of material to the permeability of air or vacuum. A. Relative permeability B. Relative permittivity C. Relative conductivity D. Relative reluctivity

A. Relative permeability

53. The property of magnetic materials of retaining magnetism after withdrawal of the magnetizing force is known as A. Retentivity B. Reluctivity C. Resistivity D. Conductivity

A. Retentivity

21. Which of the following magnetic materials can be easily magnetized in both direction? A. Soft magnetic materials B. Hard magnetic materials C. High hysteresis loss materials D. Low hysteresis loss materials

A. Soft magnetic materials

44. When a conductor is stationary and the magnetic field is moving or changing the emf induced is called A. Statically induced emf B. Mutually induced emf C. Self induced emf D. Dynamically induced emf

A. Statically induced emf

117. Flux density is measured in A. Tesla B. Weber C. Ampere- turn D. Maxwell

A. Tesla

84. Permeability means A. The conductivity of the material for magnetic lines of force B. The magnetization test in the material after exciting field has been removed C. The strength of an electromagnet D. The strength of the permanent magnet

A. The conductivity of the material for magnetic lines of force

146. The permeability of permalloy is A. Very much greater than permeability of air B. Slightly greater than permeability of air C. Slightly less than permeability of air D. Equal to the permeability of air

A. Very much greater than permeability of air

111. The quantity 10^6 Maxwell's is equivalent to one A. Weber B. Gauss C. Gilbert D. Tesla

A. Weber

77. The induced emf in a wire loop that is moved parallel to a uniform magnetic field is A. Zero B. Dependent on the area of the loop C. Dependent on the shape of the loop D. Dependent on the magnitude of the field

A. Zero

136. Electron is a Greek word for A. amber B. Fire C. Stone D. Heat

A. amber

68. All magnetic field originates from A. moving electric charge B. Iron atoms C. Magnetic domain D. Permanent magnets

A. moving electric charge

119. One ampere- turn is equivalent to __________ gilberts. A. 1.16 B. 1.26 C. 1.36 D. 1.46

B. 1.26

78. When a wire loop is rotated in a magnetic field the direction of the induced emf changes one in every _______ revolution A. 1/3 B. 1/2 C. 1/4 D. 2/3

B. 1/2

98. The K shell or the first shell has how many permissible number of orbiting electrons? A. 1 B. 2 C. 3 D. 4

B. 2

120. The magnetic flux of 2000 lines is how many Maxwells? A. 1000 B. 2000 C. 4000 D. 8000

B. 2000

100. A germanium atom has an atomic weight of 72. How many neutrons are there? A. 32 B. 40 C. 34 D. 36

B. 40

133. Hydrogen is an example of a ________ material. A. Paramagnetic B. Diamagnetic C. Ferromagnetic D. Non- magnetic

B. Diamagnetic

88. The emission of electrons from hot bodies is called A. Radiation effect B. Edison effect C. Skin effect D. Half effect

B. Edison effect

46. The branch of Engineering which deals with the magnetic effect of electric current is known as A. Magnetism B. Electromagnetism C. Electrical engineering D. Electronics engineering

B. Electromagnetism

138. What principle states that each electron in an atom must have a different set of quantum numbers? A. Inclusion principle B. Exclusion principle C. Quantum principle D. Electron principle

B. Exclusion principle

2. The magnitude of the induced emf in a coil is directly proportional to the rate of change of flux linkages. This is known as A. Joule's Law B. Faraday's second law of electromagnetic induction C. Faraday's first law of electromagnetic induction D. Coulomb's Law

B. Faraday's second law of electromagnetic induction

48. The current of electric circuit is analogous to which quantity of a magnetic circuit A. Mmf B. Flux C. Flux density D. Reluctivity

B. Flux

71. When the ferromagnetic substance is inserted in a current- carrying solenoid, the magnetic field is A. Greatly decreased B. Greatly increased C. Slightly decreased D. Slightly increased

B. Greatly increased

14. Who discovered the relationship between magnetism and electricity that serves as the foundation for the theory of electromagnetism? A. Luigi Galvani B. Hans Christian Oersted C. Andre Ampere D. Charles Coulomb

B. Hans Christian Oersted

7. If the solenoid is gripped by the right hand with the fingers pointing the direction of current flow, the outstretched thumb will then point the north pole. This is known as A. Right hand rule B. Helix rule C. End rule D. Cork screw rule

B. Helix rule

94. The simplest type of atom to exist is the ____________ atom. A. Helium B. Hydrogen C. Boron D. Oxygen

B. Hydrogen

35. Defined as a closed path in which magnetic induction or flux flows A. Electric circuit B. Magnetic circuit C. Electronic circuit D. Electromagnetic circuit

B. Magnetic circuit

109. Which of the following is a vector quantity? A. Magnetic potential B. Magnetic field intensity C. Magnetic permeability D. Flux density

B. Magnetic field intensity

65. One that has magnetic poles produced by internal atomic structure with no external current necessary A. Diamagnetic B. Permanent magnets C. Paramagnetic D. Electromagnetic

B. Permanent magnets

142. Residual magnetism refers to the flux density, which exists in the iron core when the magnetic field intensity is A. Minimized B. Reduced to zero C. Maximize D. Unity

B. Reduced to zero

30. The property of a material which opposes the creation of magnetic flux in it A. Resistance B. Reluctance C. Permeance D. Conductance

B. Reluctance

20. Referred to as the specific reluctance of a material A. Resistivity B. Reluctivity C. Conductivity D. Permeability

B. Reluctivity

140. Which of the following statements is TRUE? A. Silicon dioxide is a good B. The current carriers in conductors are valence electrons C. For conductors, the valence electron are strongly attracted to the nucleus D. The valence electrons are located in the nucleus of an atom

B. The current carriers in conductors are valence electrons

91. The contribution to the ionization in an ionization chamber by electrons liberated from the walls. A. Skin effect B. Walt effect C. Hall effect D. Edison effect

B. Walt effect

113. What is the SI unit of magnetic flux? A. Tesla B. Weber C. Maxwell D. Gauss

B. Weber

148. The force between two magnetic poles is ____________ their poles strength. A. equal to B. directly proportional to C. inversely proportional to D. directly proportional to the square root of

B. directly proportional to

70. The magnetic field inside a solenoid A. is zero B. is uniform C. increases with distance from the axis D. decreases with distance from the axis

B. is uniform

97. The diameter of a hydrogen atom is approximately ________cm. A. 1.1 x 10^-6 B. 1.1 x 10^-7 C. 1.1 x 10^-8 D. 1.1 x 10^-9

C. 1.1 x 10^-8

101. How many neutrons does a copper atom have? A. 32 B. 33 C. 34 D. 29

C. 34

114. What is the unit of magnetomotive force? A. Volt B. Tesla C. Ampere - turn D. Weber

C. Ampere - turn

23. A law establishing the fact that the algebraic sum of the rises and drops of the mmf around a closed loop of a magnetic circuit is equal to zero. A. Kirchhoff's circuital law B. Maxwell's circuital law C. Ampere's circuital law D. Coulomb's circuital law

C. Ampere's circuital law

112. What is the unit of reluctance? A. Maxwell B. Gauss C. At/Wb D. Weber

C. At/Wb

9. A law that states that the current in a thermionic diode varies directly with the three-halves power of anode voltage and inversely with the square of the distance between the electrodes, provided operating conditions are such that the current is limited only by the space charge. A. Hall's law B. Joule's law C. Child's law D. Coulomb's law

C. Child's law

55. The amount of magnetizing force to counter balance the residual magnetism of a magnetic material is referred to as A. Reluctivity B. Susceptivity C. Coercivity D. Retentivity

C. Coercivity

41. If the right handed bottle-opener cork screw is assumed to be along the conductor so as to advance in the direction of current flow, the motion of its handle will indicate the direction of magnetic flux produced around the conductor. This is known as A. Right hand rule B. Left hand rule C. Cork screw rule D. End rule

C. Cork screw rule

149. The magnetic energy stored in an inductor is ______ current. A. Directly proportional to B. Inversely proportional to C. Directly proportional to the square of D. Inversely proportional to the square of

C. Directly proportional to the square of

82. A group of magnetically aligned atoms is called A. Range B. Lattice C. Domain D. Crystal

C. Domain

95. What revolves about the positive nucleus in a definite orbit? A. Atom B. Proton C. Electron D. Neutron

C. Electron

28. Whenever a flux inking a coil or current changes, an emf is induced in it. This is known as A. Joule's LawC. Faraday's first law of electromagnetic induction B. Coulomb's Law C. Faraday's first law of electromagnetic induction D. Faraday's second law of electromagnetic induction

C. Faraday's first law of electromagnetic induction

38. Whenever a conductor cuts magnetic flux, an emf is induced in it. This is known as A. Coulomb's law B. Joule's law C. Faraday's law D. Ohm's law

C. Faraday's law

134. Cobalt is an example of a _______ material. A. Paramagnetic B. Diamagnetic C. Ferromagnetic D. Non- magnetic

C. Ferromagnetic

15. Materials that have very high permeabilities (hundreds and even thousands times of that of free space) A. Paramagnetic B. Non- magnetic C. Ferromagnetic D. Diamagnetic

C. Ferromagnetic

57. Defined as the number of lines per unit area through any substance in a plane at right angles to the lines of force A. Flux B. Flux lines C. Flux density D. Flux intensity

C. Flux density

87. Small voltages generated by a conductor with current in an external magnetic field. A. Skin effect B. Magnetic effect C. Hall effect D. Flywheel Effect

C. Hall effect

90. An effect which is generally used in the gausameter to measure flux density. A. Skin effect B. Magnetic effect C. Hall effect D. Flywheel effect

C. Hall effect

104. An alloy of 40 percent iron and 60 percent nickel. A. Alnico B. Permalloy C. Hipernik D. Manganin

C. Hipernik

61. The lagging effect between flux density of the material and the magnetizing force applied A. Permeance B. Eddy current C. Hysteresis D. Reluctance

C. Hysteresis

131. An atom or a group of atoms that carries a net electric charge. A. Positive ion B. Negative ion C. Ion D. Electron

C. Ion

10. Who developed the electromagnetic theory of light in 1862? A. Heinrich Rudolf Hertz B. Wilhelm Rontgen C. James Clerk Maxwell D. Andre Ampere;

C. James Clerk Maxwell

67. Used to maintain strength of magnetic field A. Container B. Air gap C. Keeper D. Source

C. Keeper

45. Which of the following is a natural magnet? A. Steel B. Magnesia C. Lodestone D. Soft iron

C. Lodestone

32. A substance that attracts pieces iron A. Conductor B. Semiconductor C. Magnet D. All of the above

C. Magnet

17. The straight line passing through the two poles of magnet is called A. Real axis B. Cartesian axis C. Magnetic axis D. Imaginary axis

C. Magnetic axis

24. The phenomenon by which a magnetic substance becomes a magnet when it is place near a magnet A. Magnetic effect B. Magnetic phenomenon C. Magnetic induction D. Electromagnetic induction

C. Magnetic induction

60. The ratio between the intensity of magnetization produced in a substance to the magnetizing force producing it A. Magnetic Reluctivity B. Magnetic Resistivity C. Magnetic susceptibility D. Magnetic conductivity

C. Magnetic susceptibility

116. The unit of flux is _____________ in cgs system. A. Tesla B. Gilbert C. Maxwell D. Oersted

C. Maxwell

49. It is the reciprocal of reluctance and implies the case of readiness with which magnetic flux is developed. A. Resistance B. Conductance C. Permeance D. Inductance

C. Permeance

139. The energy stored in an electrostatic field or electromagnetic field is called A. Electromagnetic energy B. Kinetic energy C. Potential energy D. Rest energy

C. Potential energy

54. The quantity of magnetism retained by a magnetic material after withdrawal of the magnetizing force is called A. Leftover magnetism B. Hysteresis C. Residual magnetism D. Coercivity

C. Residual magnetism

129. Which element has four valence electrons? A. Conductor B. Insulator C. Semiconductor D. Semi- insulator

C. Semiconductor

106. The idea of preventing one component from affecting another through their common electric and magnetic field is referred to as A. Hall effect B. Grounding C. Shielding D. Limiting

C. Shielding

81. Paramagnetic substance has a relative permeability of A. Slightly less than one B. Equal to one C. Slightly equal to one D. Very much greater than one

C. Slightly equal to one

66. Magnetic effects of the earth as a huge magnet with north and south poles. A. Diamagnetic B. Ferromagnetic C. Terrestrial magnetism D. Terrestrial ferromagnetism

C. Terrestrial magnetism

79. The magnetic flux through a wire loop in a magnetic field does not depend on A. The area of the loop B. The magnitude of the field C. The shape of the loop D. The angle between the plane of the loop and the direction

C. The shape of the loop

135. The evaporation of electrons from a heated surface is called A. Radiation B. Convection C. Thermionic emission D. Conduction

C. Thermionic emission

85. _________ is an electromagnet with its core in the form of a close magnetic ring. A. Solenoid B. Paraboloid C. Toroid D. Cycloid

C. Toroid

19. Define as that pole which when placed in air from a similar and equal pole repels it with a force of newtons A. North pole B. South pole C. Unit pole D. Magnetic pole

C. Unit pole

89. The ability of a mechanically stressed ferromagnetic wire to recognize rapid switching of magnetization when subjected to a dc magnetic field. A. Wartheim effect B. Wiedemann effect C. Wiegand effect D. Edison effect

C. Wiegand effect

118. The customary energy unit in atomic and nuclear physics is A. Joule B. Volt- coulomb C. electron-volt D. Walt- second

C. electron-volt

123. One electron volt (1 eV) is equivalent to ____ joules A. 1.3 x 10^-19 B. 1.4 x 10^-19 C. 1.5 x 10^-19 D. 1.6 x 10^-19

D. 1.6 x 10^-19

125. The unit of electrical energy is A. Joule B. Watt- second C. Kilowatt- hour D. All of these

D. All of these

27. Lenz' law states that the direction of the induced emf and hence current A. Is determined by the rate of current flux B. Is found by the right hand rule C. Is found by the left hand rule D. Always opposes the cause producing it

D. Always opposes the cause producing it

26. Who demonstrated that there are magnetic effects around every current-carrying conductor and that current-carrying conductors can attract and repel each other just like magnets? A. Luigi Galvani B. Hans Christian Oersted C. Charles Coulomb D. Andre Ampere

D. Andre Ampere

93. All matters (gas, liquid and solid) are composed of A. Neutrons B. Particles C. Electrons D. Atoms

D. Atoms

3. The force of attraction or repulsion between two magnetic poles is inversely proportional to the square of the distance between them. This is known as A. Newton's first law B. Faraday's first law of electromagnetic induction C. Coulomb's first law D. Coulomb's second law

D. Coulomb's second law

29. Which of the following materials has permeability slightly less than that of free space? A. Paramagnetic B. Non- magnetic C. Ferromagnetic D. Diamagnetic

D. Diamagnetic

16. If on looking at any one end of a solenoid; the direction of current flow is found to be clockwise then the end under observation is a south pole. This is known as A. Right hand rule B. Left hand rule C. Cork screw rule D. End Rule

D. End Rule

108. Flux linkages equals A. Flux times area of core B. Flux times number of turns times area of core C. Flux times number of turns times length of core D. Flux times number of turns

D. Flux times number of turns

144. The core of a magnetic equipment uses a magnetic material with A. Least permeability B. Low permeability C. Moderate permeability D. High permeability

D. High permeability

58. Defined as the flux density produced in it due to its own induced magnetism A. Magnetic field intensity B. Electric field intensity C. Electromagnetic field intensity D. Intensity magnetization

D. Intensity magnetization

83. The force between two magnetic poles varies with the distance between them. The variation is _________ to the square of that distance. A. Equal B. Greater than C. Directly proportional D. Inversely proportional

D. Inversely proportional

132. Hysteresis refers to the _______________ between flux density of the material and the magnetizing force applied. A. Leading effect B. Ratio C. Equality D. Lagging effect

D. Lagging effect

56. The ratio of the total flux (flux in iron path) to the useful flux (flux in air gap) A. Leakage flux B. Leakage current C. Leakage coefficient D. Leakage factor

D. Leakage factor

39. A law that states that the polarity of the induced voltage will oppose the change in magnetic flux causing the induction. A. Joule's law B. Faraday's law C. Coulomb's law D. Lenz' law

D. Lenz' law

147. A t/m is a unit of A. Mmf B. Emf C. Reluctance D. Magnetizing force

D. Magnetizing force

22. The force which set ups or tends to set up magnetic flux in a magnetic circuit A. Dynamic force B. Electromotive force C. Potential difference D. Magnetomotive force

D. Magnetomotive force

102. Bonding of atoms that is due to the force of attraction between positive ions and a group of negative ions A. Ionic bond B. Covalent Bond C. Electrostatic Bond D. Metallic bond

D. Metallic bond

96. The uncharged particles which have no effect on its atomic charge. A. Nucleons B. Electrons C. Protons D. Neutrons

D. Neutrons

145. Which of the following is a paramagnetic material? A. Carbon B. Copper C. Bismuth D. Oxygen

D. Oxygen

50. The ability of a material to conduct magnetic flux through it. A. Permittivity B. Reluctivity C. Conductivity D. Permeability

D. Permeability

137. Gases whose particles are charged are known as A. Conductors B. Insulators C. Gaseous Conductors D. Plasma

D. Plasma

40. If you hold the conductor with right hand so that the stretched thumb points in the direction of the current, then encircling fingers will give the direction of magnetic lines of force round the conductor. This is known as A. Left hand cork screw rule B. Right hand cork screw rule C. Left hand rule D. Right hand rule

D. Right hand rule

6. The emf induced in a coil due to the change of its own flux linked with it is called A. Mutually induced emf B. Dynamically induced emf C. Statically induced emf D. Self induced emf

D. Self induced emf

69. Magnetic fields do not interact with A. Moving permanent magnets B. Stationary permanent magnets C. Moving electric charges D. Stationary electric charges

D. Stationary electric charges

126. Electrons at the outer shell are called A. Outer shell electrons B. Inner shell electrons C. Semiconductor electrons D. Valence electrons

D. Valence electrons

143. Magnetic intensity is a A. Phasor quantity B. Physical quantity C. Scalar quantity D. Vector quantity

D. Vector quantity

12. States that the ratio of the thermal conductivity is proportional to the absolute temperature for all metals. A. Wien's displacement law B. Hartleys law C. Hall's law D. Wiedemann Franz law

D. Wiedemann Franz law

72. The magnetic field of a bar magnet most closely resembles the magnetic field of A. a horseshoe magnet B. a straight current- carrying wire C. a stream of electrons moving parallel to one another D. a current- carrying wire loop

D. a current- carrying wire loop

74. A permanent magnet does not exert a force on A. an unmagnetized iron bar B. a magnetized iron bar C. a moving electric charge D. a stationary electric charge

D. a stationary electric charge