MCQ in Electricity and Magnetism Fundamentals Part 4 | ECE Board Exam

(Last Updated On: April 12, 2018)
Electricity and Magnetism Fundamentals - MCQS Part IV

This is the Multiple Choice Questions Part 4 of the Series in Electricity and Magnetism Fundamentals as one of the Electronics Engineering topic. In Preparation for the ECE Board Exam make sure to expose yourself and familiarize in each and every questions compiled here taken from various sources including but not limited to past Board Exam Questions in Electronics Engineering field, Electronics Books, Journals and other Electronics References.

MCQ Topic Outline included in ECE Board Exam Syllabi

  • MCQs in Atomic Structure
  • MCQs in Electric Charge
  • MCQs in Ohm’s Law, Kirchoff Law, Coulomb’s Law, etc
  • MCQs in Magnetic Power
  • MCQs in Magnetic Field and Magnetic Flux
  • MCQs in Magnetic and Electric Quantities / Units
  • MCQs in Magnetic/Electromagnet Principles

Continue Practice Exam Test Questions Part 4 of the Series

151. How is mutual inductance between two coils decreased?

  • A. By using a common core
  • B. By moving the coils closer
  • C. By moving the coils apart
  • D. By increasing the number of turns of either coil
View Answer:

Answer: Option C

Solution:

152. A magnetic field is

  • A. The current flow through space around a permanent magnet
  • B. The force set up when current flows through a conductor
  • C. The force that drives current through a resistor
  • D. The force between the plates of a charged capacitor
View Answer:

Answer: Option B

Solution:

153. Ohm’s law can be used only to a _________ circuit or component.

  • A. Unilateral
  • B. Exponential
  • C. Trivalent
  • D. Linear
View Answer:

Answer: Option D

Solution:

154. When the current flows, the magnetic field conductor is in what direction?

  • A. The same as the current direction
  • B. Opposite the current direction
  • C. Omnidirectional
  • D. In the direction determined by the left hand rule
View Answer:

Answer: Option D

Solution:

155. The magnetic field around the conductor is determined by the

  • A. Size of the conductor
  • B. Amount of current
  • C. Current divided by the resistance
  • D. Resistance divided by the current
View Answer:

Answer: Option B

Solution:

156. Back emf refers to the

  • A. Current equal to the applied emf
  • B. Opposing emf
  • C. Current opposing the applied emf
  • D. Voltage opposing the applied emf
View Answer:

Answer: Option D

Solution:

157. The magnetic flux through a coil changes. This results to the induced emf acting in a direction as to

  • A. Oppose the change
  • B. Aid the change
  • C. Either oppose or aid the change
  • D. Neither oppose nor aid the change
View Answer:

Answer: Option A

Solution:

158. A magnetic flux of 2.5 x 10^4 Wb through an area of 5 x 10^4 square meters results in

  • A. 5 Wb
  • B. 0.5 Tesla of flux density
  • C. 5 x 10^-5 Wb of flux
  • D. 5000 Tesla of flux density
View Answer:

Answer: Option C

Solution:

159. If a 20 V potential is applied across a relay coil with 50 turns having 1 Ω of resistance, the total magnetomotive producing magnetic flux in the circuit is

  • A. 10 Wb
  • B. 50 T
  • C. 1000 A t/m
  • D. 1000 A.t
View Answer:

Answer: Option D

Solution:

160. What is the reluctance of a magnetic path having a length of 2 x 10^-3 m and cross- sectional area of 2.5 x 10^-3 m^2?

  • A. 6366 A.t/Wb
  • B. 6000 A.t/Wb
  • C. 8 x 10^-3 A.t/Wb
  • D. 0.8 A.t/Wb
View Answer:

Answer: Option A

Solution:

161. Calculate the permeability (in T/A. t/m) of a magnetic material that has a relative permeability of 300

  • A. 3.78 x 10^-4
  • B. 3.78 x 10^-5
  • C. 3.78 x 10^-3
  • D. 3.78 x 10^-6
View Answer:

Answer: Option A

Solution:

162. Calculate the flux density that will be produced by the field intensity of 2000 a. t/m for a permeability of 126 x 10^-6 T/A.t/m

  • A. 0.252 G
  • B. 0.252 x 10^-2 T
  • C. 0.252 T
  • D. 0.252 x 10^-2 G
View Answer:

Answer: Option C

Solution:

163. How many turns are needed to produce a magnetomotive force of 1000 A.t for a coil with 6 amperes?

  • A. 6000 turns
  • B. 600 turns
  • C. 167 turns
  • D. 67 turns
View Answer:

Answer: Option C

Solution:

164. A 6- V battery is connected across a solenoid of 100 turns having a resistance of 2 Ω, Calculate the number of ampere turns?

  • A. 100
  • B. 50
  • C. 300
  • D. 600
View Answer:

Answer: Option C

Solution:

165. What determines the atomic number of an element?

  • A. The number of protons
  • B. The number of electrons
  • C. The number of neutrons
  • D. The number of neutrons and protons
View Answer:

Answer: Option A

Solution:

166. One of the solid structures in which the position of the atoms or ions are predetermined

  • A. Crystalline solid
  • B. Amorphous solid
  • C. Polycrystalline solid
  • D. Poly- amorphous solid
View Answer:

Answer: Option A

Solution:

167. Mmf in a magnetic circuit corresponds to ________ in an electric circuit

  • A. Emf
  • B. Voltage drop
  • C. Electric Field Intensity
  • D. Potential gradient
View Answer:

Answer: Option A

Solution:

168. What solid has no defined crystal structure except perhaps in the arrangement of the nearest neighboring atoms or ions?

  • A. Crystalline
  • B. Amorphous
  • C. Polycrystalline
  • D. Poly- amorphous
View Answer:

Answer: Option B

Solution:

169. Amorphous solid is also called

  • A. Crystalline
  • B. Non- crystalline
  • C. Polycrystalline
  • D. Homogenous
View Answer:

Answer: Option B

Solution:

170. A principle that states that only two electrons with different spins are allowed to exist in a given orbit

  • A. Bohr’s principle
  • B. Pauli exclusion principle
  • C. Avogadro’s principle
  • D. Coulomb’s principle
View Answer:

Answer: Option B

Solution:

171. What bond is formed when one or more electrons in the outermost energy orbit of an atom are transferred to another?

  • A. Ionic
  • B. Covalent
  • C. Metallic
  • D. Van der Waals
View Answer:

Answer: Option A

Solution:

172. In electro-mechanical conversion devices like generators and motors the reason why a small air gap is left between the rotor and stator is to

  • A. permit mechanical clearance
  • B. increase flux density in air gap
  • C. decrease the reluctance of magnetic path
  • D. complete the magnetic path
View Answer:

Answer: Option A

Solution:

173. What bond is formed when electrons in the outermost energy orbits of the atoms are shared between two or more electrons?

  • A. Ionic
  • B. Covalent
  • C. Metallic
  • D. Van der Waals
View Answer:

Answer: Option B

Solution:

174. Why is it that the magnitude of magnetomotive force required for air gap is much greater than that required for iron part of a magnetic circuit?

  • A. Because air is a gas
  • B. Because air has the highest relative permeability
  • C. Because air is a conductor of magnetic flux
  • D. Because air has the lowest relative permeability
View Answer:

Answer: Option D

Solution:

175. What type of bond is formed when there exists some form of collective interactions between the (negatively charged) electrons and (positively charged) nuclei in a solid?

  • A. Ionic
  • B. Covalent
  • C. Metallic
  • D. Van der Waals
View Answer:

Answer: Option C

Solution:

176. Permeance of a magnetic circuit is _________ the cross-sectional area of the circuit.

  • A. directly proportional to
  • B. inversely proportional to
  • C. dependent of
  • D. independent of
View Answer:

Answer: Option A

Solution:

177. Formed when there exist distant electronic interactions between (opposite) charges present in the neighboring atoms or molecules.

  • A. Ionic bond
  • B. Covalent bond
  • C. Metallic bond
  • D. Van der Waals bond
View Answer:

Answer: Option D

Solution:

178. Defined as the ratio of the volume occupied by the atoms or ions in a unit cell divided by the volume of the unit cell and is used to measure the compactness of a crystal.

  • A. Atomic packing factor (APF)
  • B. Ionic Packing Ratio (IPR)
  • C. Atomic compacting factor (ACF)
  • D. Ionic compacting ratio (ICR)
View Answer:

Answer: Option A

Solution:

179. A factor used to correct for the electrostatic forces of the more distant ions in an ionic solid.

  • A. Avogadro’s number
  • B. Planck’s constant
  • C. Boltzmann’s constant
  • D. Madelung constant
View Answer:

Answer: Option D

Solution:

180. The conduction of electricity across the surface of a dielectric is called

  • A. creepage
  • B. skin effect
  • C. surface effect
  • D. crosstalk
View Answer:

Answer: Option A

Solution:

181. A magnetic circuit carries a flux φi in the iron part and a flux φg in the air gap. What is the leakage coefficient?

  • A. φi/ φg
  • B. φi × φg
  • C. φg /φi
  • D. φi + φg
View Answer:

Answer: Option A

Solution:

182. A law stating that the magnetic susceptibilities of most paramagnetic substances are inversely proportional to their absolute temperatures.

  • A. Curie’s Law
  • B. Child’s Law
  • C. CR Law
  • D. Curie-Weiss Law
View Answer:

Answer: Option A

Solution:

183. The reluctance of the magnetic circuit is ________ relative permeability of the material comprising the circuit.

  • A. directly proportional to
  • B. inversely proportional to
  • C. independent of
  • D. dependent of
View Answer:

Answer: Option B

Solution:

184. A law relating between the magnetic and electric susceptibilities and the absolute temperatures which is followed b ferromagnets, antiferromagnets, non-polar ferroelectrics, antiferroelectrics and some paramagnets.

  • A. Curie’s Law
  • B. Child’s Law
  • C. CR Law
  • D. Curie-Weiss Law
View Answer:

Answer: Option D

Solution:

185. Theory of ferromagnetic phenomena which assumes each atom is a permanent magnet which can turn freely about its center under the influence of applied field and other magnets.

  • A. Ewing’s theory of ferromagnetism
  • B. Oersted’s ferromagnetism theory
  • C. Maxwell’s magnetic theory
  • D. Ampere’s circuital law
View Answer:

Answer: Option A

Solution:

186. The reluctance of a magnetic circuit varies with

  • A. length × area
  • B. area ÷ length
  • C. length ÷ area
  • D. length + area
View Answer:

Answer: Option C

Solution:

187. A theorem which states that an electric current flowing in a circuit produces a magnetic field at external points equivalent to that due to a magnetic shell whose bounding edge is the conductor and whose strength of the current.

  • A. Joule’s law
  • B. Faraday’s law
  • C. Volta’s theorem
  • D. Ampere’s theorem
View Answer:

Answer: Option D

Solution:

188. What is the usual value of leakage coefficient for electrical machines?

  • A. 0.5 to 1
  • B. 1 to 5
  • C. 5 to 10
  • D. 1.15 to 1.25
View Answer:

Answer: Option D

Solution:

189. The science of adapting electronics to aerospace flight.

  • A. Avionics
  • B. Aerotronics
  • C. Aerodynamics
  • D. Astrionics
View Answer:

Answer: Option D

Solution:

190. The reluctance of a magnetic circuit is not dependent on which of the following?

  • A. Number of turns of coil
  • B. Magnetomotive force
  • C. Flux density in the circuit
  • D. Current in the coil
View Answer:

Answer: Option C

Solution:

191. Another term for corona discharge.

  • A. Lightning
  • B. Sparking
  • C. Aurora
  • D. Corona Effect
View Answer:

Answer: Option C

Solution:

192. The B-H curve for ________ is a straight line passing through the origin.

  • A. cobalt
  • B. air
  • C. hardened steel
  • D. soft iron
View Answer:

Answer: Option B

Solution:

193. The phenomenon that when an electric current passes through an anisotropic crystal, there is an absorption or liberation of heat due to the non-uniformity in current distribution.

  • A. Bridgman effect
  • B. Corona effect
  • C. Dember effect
  • D. Destriau effect
View Answer:

Answer: Option A

Solution:

194. The B-H curve of ________ is not a straight line.

  • A. air
  • B. wood
  • C. silicon steel
  • D. soft iron
View Answer:

Answer: Option D

Solution:

195. If a magnetic flux cuts across 200 turns at a rate of 2 Wb/s, the induced voltage according to Faraday’s law is about

  • A. 400 V
  • B. 100 V
  • C. 200 V
  • D. 600 V
View Answer:

Answer: Option A

Solution:

196. What is the SI unit of reluctance?

  • A. At
  • B. At/m
  • C. N/Wb
  • D. At/Wb
View Answer:

Answer: Option D

Solution:

197. A magnetizing force of 1000 AT/m will produce a flux density of __________ in air.

  • A. 1.257 mWb/m^2
  • B. 0.63 Wb/m^2
  • C. 1.257 Wb/m^2
  • D. 0.63 mWb/m^2
View Answer:

Answer: Option A

Solution:

198. Hysteresis loss can be reduced by one of the following.

  • A. Increasing mmf of the circuit
  • B. Using material narrow hysteresis loop
  • C. Using ferromagnetic core
  • D. Laminating the magnetic circuit
View Answer:

Answer: Option B

Solution:

199. The core of a transformer heats up when its primary is fed from an ac source because of

  • A. permeability
  • B. ferromagnetism
  • C. reluctance of core
  • D. hysteresis loss
View Answer:

Answer: Option D

Solution:

200. Which of the following materials has the least hysteresis loop area?

  • A. soft iron
  • B. silicon steel
  • C. hard steel
  • D. wrought iron
View Answer:

Answer: Option B

Solution:

Questions and Answers in Electricity and Magnetism Fundamentals

Following is the list of multiple choice questions in this brand new series:
MCQ in Electricity and Magnetism Fundamentals
PART 1: MCQs from Number 1 – 50                        Answer key: PART I
PART 2: MCQs from Number 51 – 100                   Answer key: PART II
PART 3: MCQs from Number 101 – 150                 Answer key: PART III
PART 4: MCQs from Number 151 – 200                 Answer key: PART IV
PART 5: MCQs from Number 201 – 250                 Answer key: PART V
PART 6: MCQs from Number 251 – 300                 Answer key: PART VI
PART 7: MCQs from Number 301 – 350                 Answer key: included
PART 8: MCQs from Number 351 – 400                Answer key: included
PART 9: MCQs from Number 401 – 450                 Answer key: included
PART 10: MCQs from Number 451 – 500                 Answer key: included

Complete List of MCQ in Electronics Engineering per topic

MCQ in Electricity and Magnetism Fundamentals Part 4 | ECE Board Exam
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