# 200+ Electromagnetism Objective Questions and Answers

In this article, we shared the electromagnetism objective questions and answers for electrical and electronics engineers.

## Electromagnetism Objective Questions

The below list provides all the multiple-choice questions related to electromagnetism.

Answers are available at the bottom of the article.

1. Which of the following is a vector quantity?

2. What is the value of the magnetic vector potential due to an infinitesimally small current element, evaluated at an infinite distance from it?

3. A permanent magnet

4. Reciprocal of reluctance is

5. In a magnetic material, hysteresis loss takes place primarily due to

6. The magnitude of induced emf in a conductor depends upon the

7. The magnetic field strength of an air-cored coil can be increased by

8. The uniform magnetic field is

9. Laminated cores in electrical machines are used to reduce

10. Tesla is a unit of

11. Hysteresis loss least depends on

12. The hysteresis loss is caused by

13. Energy stored by a coil is doubled when its current is increased by

14. When a plane wave propagates in a dielectric medium

15. In which of the materials the spin moments associated with two sets of atoms are aligned antiparallel to each other?

16. The tubes of force within the magnetic material are known as

17. Which of the following is a ferromagnetic material?

18. The direction of magnetic lines of force is

19. The magnetic reluctance of a material

20. Degaussing is the process of

21. A conductor of length L has current I passing through it when it is placed parallel to a magnetic field. The force experienced by the conductor will be

22. If the area of the hysteresis loop of a material is large, the hysteresis loss in this material will be

23. While comparing magnetic and electric circuits, the flux of the magnetic circuit is compared with which parameter of the electrical circuit?

24. Two coils are coupled in such a way that the mutual inductance between them is 16 mH. If the inductances of the coils are 20 mH and 80 mH respectively, the coefficient of coupling is

25. According to steinmetz hysteresis law, hysteresis loss in a material is proportional to

26. A magnet does not attract

27. In a simple magnetic field the strength of magnet flux

28. An air gap is usually inserted in magnetic circuits so as to

29. For a perfect conductor, the field strength at a distance equal to the skin depth is X% of the field strength at its surface. The value of â€˜X%â€™ is

30. Consider the following statements:

In the case of diamagnetic materials, the magnetic susceptibly is

1. positive.

2. negative.

3.independent of temperature.

4.inversely proportional to temperature.

Of these statements

31. A ferrite core has less eddy current loss than an iron core because

32. Core of an electromagnet should have

33. In a magnetic material hysteresis loss takes place primarily due to

34. Iron is a

35. If a copper conductor is moved across a magnetic field

36. Permeance is to reluctance as conductance is to

37. The electromagnet is made of

38. Those magnetic materials are best suited for making armature and transformer cores which have____ permeability and____ hystersis loss.

39. The commonly used material for shielding or screening magnetism is

40. How does the. magnetic compass needle behave in a magnetic field?

41. The bar magnet has

42. The shape of B-H curve for air gap is

43. Out of the following statements, concerning an electric field, which statement is not true ?

44. The surface integral of the electrical field intensity is the

45. The main constituent of permalloy is

46. Two coils having equal resistances but different inductances are connected in series.

The time constant of the series combination is the

47. Ferrites are a sub-group of

48. The property of a material which opposes the production of magnetic flux in it is known as

49. Conductance is analogous to

50. The magnetising force (H) and magnetic flux density (B) are connected by the relation

51. Conductivity is analogous to

52. The unit of magnetic flux is

53. Supermagnetic materials are composed of

54. Which of the following statements should be true if one compares the hysteresis loops of hard and soft magnetic materials?

1. Hysteresis loss of hard magnetic material will be less than that of soft material.

2. Coercivity of hard material will be greater than that of soft material.

3. Retentivity of two materials will always be equal.

Select the correct answer using the codes given below Codes:

55. The use of permanent magnets is not made in

56. What is the value of total electric flux coming out of a closed surface?

57. According to Faradayâ€™s law of electromagnetic induction an emf is induced in a conductor whenever it

58. A certain amount of current flows through a ring-shaped coil with a fixed number of turns.

How does the magnetic induction B varies inside the coil if an iron core is threaded into coil without dimensional change of coil?

59. Two long parallel conductors carry 100 A. If the conductors are separated by 20 mm, the force per meter of length of each conductor will be

60. Magnetostriction is a phenomenon of

61. The magnetic susceptibility of a paramagnetic material is

62. The principle of dynamically induced emf is utilized in a

63. Two parallel wires separated by a distance dare carrying a current in the same direction. The magnetic field along a line running parallel to these wires and midway between them

64. A coil with a certain number of turns has a specified time constant. If the number of turns is doubled, its time constant would

65. For which of the following materials the net magnetic moment should be zero?

66. A 300 mm long conductor is carrying a current of 10 A and is situated at right angles to a magnetic field having a flux density of 0.8 T the force on the conductor will be

67. The unit of retentivity is

68. Which of the following statements is correct?

69. Which of the following is not a unit of flux?

70. The unit of relative permeability is

71. A coil wound over an iron ring carries a certain current and establishes flux in the ring. If the area of the x-section of the ring is doubled, the flux density in the core

72. Reluctance offered by the magnetic circuit depends upon

73. Which of the following materials are diamagnetic?

74. Remanent magnetism is one which

75. The coupling between two magnetically coupled coils is said to be ideal if the coefficient of coupling is

76. Which law is synonymous to the occurrence of diamagnetism?

77. The conductance of an electrical circuit is analogous to the magnetic circuit by

78. The magnetism left in the iron after the exciting field has been removed is known as

79. The magnetic materials exhibit the property of magnetization due to

80. Magnetostriction is a phenomenon whereby the magnetization of a ferromagnetic material leads to a change in

81. The unit of flux is the same as that of

82. Which of the following is correct?

83. The rate of rise of current through an inductive coil is maximum

84. The most effective and quickest way of making a magnet from soft iron is by

85. Air exhibits

86. When both the inductance and resistance of a coil are doubled the value of

87. Î” x E = dB/dt is derived from

88. Which of the following type of materials are not very important for engineering applications?

89. The magnitude of the force acting on a current-carrying conductor placed in a magnetic field is independent of

90. An electric field is parallel but opposite to a magnetic field. Electrons with some initial velocity enter the region of the fields at an angle Î¸ along the direction of the electric field. The electron path will be

91. Energy stored by a coil is doubled when its current is increased by____ percent.

92. When a battery of E volts is suddenly applied across an ideal inductance of L henry, the current through inductance will be

93. Which of the following statements associated with the magnetic field is correct?

94. Core of an electromagnet should have

95. Unit for the quantity of electricity is

96. Which of the following is the unit of magnetic flux density?

97. The relative permeability of a ferromagnetic material is

98. The magnetic materials exhibit the property of magnetization because of

99. The two conductors of a transmission line carry equal current I in opposite directions. The force on each conductor is

100. What will be the magnetic potential difference across the air gap of 2 cm length in the magnetic field of 200 AT/m?

101. Soft magnetic material is

102. Linkage flux per unit current is called

103. A coil of 1,000 turns is wound on a core. A current of 1 A flowing through the coil creates a core flux 1 m Wb. The energy stored in the magnetic field is

104. The energy stored in the magnetic field of a solenoid 30 cm long and 3 cm diameter wound with 1,000 turns of wire carrying a current of 10 A is

105. The____ materials are a bit inferior conductors of magnetic flux than air

106. Air gap has____ reluctance as compared to iron or steel path

107. If in an iron cored coil the iron core is removed so as to make the air-cored coil, the inductance of the coil will be

108. The emf induced in a coil due to the relative motion of a magnet is independent of

109. Two identical coils of negligible resistance, when connected in series across a 50Hz fixed voltage source, draw a current of 10 A. When the terminals of one of the coils are reversed, the current drawn is 8 A. The coefficient of coupling between the two coils is

110. The attraction capacity of the electromagnet will increase if the

111. The overall inductance of two coils connected in series, with mutual inductance aiding self-inductance is L1 with mutual inductance opposing self-inductance the overall inductance is L2. The mutual inductance M is given by

112. The change of the cross-sectional area of a conductor in a magnetic field will affect

113. A 200 turn coil having an axial length of 30 mm and a radius of 10 mm is pivoted in a magnetic field having a flux density of 0.8 T. If the coil carries a current of 0.5 A, the torque acting on the coil will be

114. The stray line of magnetic flux is defined as

115. Magnetic flux density emerging out of a closed surface is

116. Susceptibility is positive for

117. Two conducting thin coils X and Y (identical except for a thin cut in coil Y) are placed in a uniform magnetic field which is decreasing at a constant rate. If the plane of the coils is perpendicular to the field lines, which of the following statement is correct? As a result, emf is inducted in

118. When a single turn coil rotates in a uniform magnetic field, at a uniform speed the induced emf will be

119. The relative permeability of____materials is not constant

120. Permanent magnets are normally made of

121. Inductance has the dimensions of

122. The retentivity (a property) of material is useful for the construction of

123. An air gap is usually inserted in magnetic circuits to

124. An infinitely long straight conductor located along Z-axis carries a current I in the +ve Z-direction. The magnetic field at any point P in the X-Y plane is in which direction?

125. The magneto-motive force is

126. The field at any point on the axis of a current-carrying coil will be

127. A rectangular magnet of magnetic moment M is cut into two piece of the same length, the magnetic moment of each piece will be

128. The coils having self-inductance of 10 mH and 15 mH and an effective inductance of 40 mH, when connected in series aiding. What will be the equivalent inductance if we connect them in series opposing?

129. Main causes of noisy solenoid are

130. A permeable substance is one

131. Ferrites are____ materials

132. Which of the following is expected to have the maximum permeability?

133. Image theory is applicable to problems involving

134. A material for good magnetic memory should have

135. When two ends of a circular uniform wire are joined to the terminals of a battery, the field at the center of the circle

136. Which of the following statements holds of the divergence of electric and magnetic flux densities?

137. Soft magnetic materials have

138. When a magnet is in motion relative to a coil the induced e.m.f. does not depend upon

139. If the two conductors carry current in opposite directions there will be

140. When a piece of iron is placed in a magnetic field

141. A ferromagnetic core subjected to cycles of magnetisation will exhibit hysteresis when the cycle is

142. Mutual inductance between two magnetically coupled coils depends on the

143. The working of a meter is based on the use of a permanent magnet. In order to protect the meter functioning from stray magnetic fields

144. The inductance of a long solenoid of length 1,000 mm wound uniformly with 3000 turns on a cylindrical paper tube of 60 mm diameter is

145. The susceptibility of paramagnetic materials generally lies between

146. The left hand rule correlates to

147. Lower the self inductance of a coil

148. The force experienced by a current carrying conductor lying parallel to a magnetic field is

149. The inductance of a single layer solenoid of 10 turns is 5 Î¼H. Which one cf the following is the correct value of inductance when the number of turns is 20 and the length is doubled?

150. A material which is slightly repelled by a magnetic field is known as

151. Which of the following statement(s) is/are correct?â€‹

1. Ferromagnetic substances have very large negative values of susceptibility.

2. Diamagnetic substances have very small negative values of suceptibility.

3. Paramagnetic substances have very small positive values of susceptibility.

4. The permeability of diamagnetic substances is slightly greater than unity.

152. The magnetic field intensity (in A/m) at the centre of a circular coil of diameter 1 m and carrying a current of 2 A is

153. Aluminium and platinum are____materials.

154. The property of a material which opposes the creation of magnetic flux in it is known as

155. A keeper is used for

156. One maxwell is equal to

157. The electromagnet has 50 turns and a current of 1 A flows through the coil. If the length of the magnet circuit is 200 mm, what is the magnetic field strength ?

158. Which of the following inductors will have the least eddy current losses?

159. Paramagnetic materials have a relative permeability

160. Hard steel is suitable for making permanent magnets because

161. Those materials are well suited for making permanent magnets which have____ retentivity and____ coercivity

162. In case all the flux from the current in coil 1 links with coil 2, the coefficient of coupling will be

163. Materials subjected to rapid reversal of magnetism should have

164. The force between two long parallel conductors is inversely proportional to

165. A keeper is used to

166. Strength of an electromagnet can be increased by

167. Iron loss is known as

168. The ratio of intensity of magnetization to the magnetisation force is known as

169. The area of hysteresis loss is a measure of

170. Hysteresis loop in case of magnetically hard materials is more____ in shape as compared to magnetically soft materials.

171. The relative permeability is less than unity is case of

172. What will be the current passing through the ring shaped air cored coil when number of turns is 800 and ampere turns are 3200?

173. One tesla is equal to

174. Magnetism of a magnet can be destroyed by

175. The coercive force in a ferromagnetic material is related to the

176. The unit(s) of inductance is/are

177. Magnetising steel is normals difficult because

178. Indicate which of the following material does not retain magnetism permanently.

179. In all cases of electromagnetic induction, an induced voltage will cause a current to flow in a closed circuit in such a direction that the magnetic field which is caused by that current will oppose the change that produces the current, is the original statement of

180. The magnetic field required to reduce the residual magnetisation to zero is called

181. Substances winch have permeability less than the permeability of free space are known as

182. Which part of the magnetic path requires largest m.m.f ?

183. The magnetisation and applied field in ferromagnetic materials are related

184. An open coil has

185. The unit of reluctance is

186. Reciprocal of permeability is

187. In order to minimise loss due to hysteresis the magnetic material should have

188. A straight conductor of circular x-section carries a current. Which one of the following statements is true in this regard?

189. If a current carrying conductor is placed in a magnetic field, the mechanical force experienced on the conductor is determined by

190. The materials having low retentivity are suitable for making

191. Consider the following statements:

The force per unit length between two stationary parallel wires carrying (steady) currents

1. is inversely proportional to the separation of wires.

2. is proportional to the magnitude of each current.

3. satisfies Newtonâ€™s third law.

192. A magnetic field exists around

193. âˆ‡B is based on

194. Which of the following statements is correct?

195. In order to minimise loss due to hysteresis, the magnetic material should have

196. The Biot-savartâ€™s law is a general modification of

197. A magnetic circuit requires 800 AT to produce a certain quantity of flux in magnetic circuit.

If its excitation coil has 100 turns and 5 Ï‰ resistance, the voltage to be applied in exciting coil is

198. Hysteresis loss least depends on

199. Magnetic current is composed of which of the following?

200. Gilbert is a unit of

201. Materials subjected to rapid reversals of magnetism should have

202. The initial rate of rise of current through a coil of inductance 10 H when suddenly connected to a D.C. supply of 200 V is____ A/s

203. Relative permeability of vacuum is

204. Which of the following statements is correct?

205. Permeability in a magnetic circuit corresponds to____ in an electric circuit.

206. Flemingâ€™s left hand rule is used to find

207. The area of hysteresis loop is a measure of

208. The bar magnet has

209. In the left hand rule, forefinger always represents

210. The mutual inductance between two coupled coils is 10 mH.â€‹

If the turns in one coil are doubled and that in the other are halved, then the mutual inductance will be

211. Temporary magnets are used in

212. The transformer cores operating at microwave frequency range, are usually made of

213. Which of the following statements associated with inductors is wrong?

214. Point out the wrong statement.

Magnetic leakage is undesirable in electric machines because it

215. If a copper disc is rotated rapidly below a freely suspended magnetic needle, the magnetic needle shall start rotating with a velocity

216. An electromagnetic field is radiated from

217. Which of the following is a vector quantity?

218. The laws of electromagnetic induction (Faradayâ€™s md Lenzâ€™s laws) are summarized in the following equation:

219. Silicon steel is used in electrical machines because it has

220. When an iron piece is placed in a magnetic field

221. At a certain current, the energy stored in an iron-cored coil is 1,000 J and its copper loss is 2,000W. The time constant (in seconds) of the coil is

222. There is a constant homogeneous magnetic field pointing in a vertical direction. A metallic wire in the form of a square is rotated about a horizontal axis passing through the middle points of its opposite arms. The emf generated in the square is