You dont have javascript enabled! Please enable it! MCQ in Electricity and Magnetism Fundamentals Part 4 | ECE Board Exam

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

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

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

#### Continue Practice Exam Test Questions Part 4 of the Series

Choose the letter of the best answer in each questions.

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

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

Solution:

153. Ohmโs law can be used only to a _____________ circuit or component.

A. Unilateral

B. Exponential

C. Trivalent

D. Linear

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

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

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

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

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

Solution:

159. If a 20 V potential is applied across a relay coil with 50 turns having 1 โฆ 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

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

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

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

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

Solution:

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

A. 100

B. 50

C. 300

D. 600

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

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

Solution:

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

A. Emf

B. Voltage drop

C. Electric Field Intensity

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

Solution:

169. Amorphous solid is also called

A. Crystalline

B. Non- crystalline

C. Polycrystalline

D. Homogenous

Solution:

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

A. Bohrโs principle

B. Pauli exclusion principle

D. Coulombโs principle

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

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

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

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

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

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

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

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)

Solution:

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

B. Planckโs constant

C. Boltzmannโs constant

Solution:

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

A. creepage

B. skin effect

C. surface effect

D. crosstalk

Solution:

181. A magnetic circuit carries a flux ฯi in the iron part and a flux ฯg in the air gap. What is the leakage coefficient?

A. ฯi/ ฯg

B. ฯi ร ฯg

C. ฯg /ฯi

D. ฯi + ฯg

Solution:

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

A. Curieโs Law

B. Childโs Law

C. CR Law

D. Curie-Weiss Law

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

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. Curieโs Law

B. Childโs Law

C. CR Law

D. Curie-Weiss Law

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. Ewingโs theory of ferromagnetism

B. Oerstedโs ferromagnetism theory

C. Maxwellโs magnetic theory

D. Ampereโs circuital law

Solution:

186. The reluctance of a magnetic circuit varies with

A. length ร area

B. area รท length

C. length รท area

D. length + area

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. Jouleโs law

C. Voltaโs theorem

D. Ampereโs theorem

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

Solution:

189. The science of adapting electronics to aerospace flight.

A. Avionics

B. Aerotronics

C. Aerodynamics

D. Astrionics

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

Solution:

191. Another term for corona discharge.

A. Lightning

B. Sparking

C. Aurora

D. Corona Effect

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

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

Solution:

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

A. air

B. wood

C. silicon steel

D. soft iron

Solution:

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

A. 400 V

B. 100 V

C. 200 V

D. 600 V

Solution:

196. What is the SI unit of reluctance?

A. At

B. At/m

C. N/Wb

D. At/Wb

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

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

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

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

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: MCQ from Number 1 โ 50                        Answer key: PART 1
PART 2: MCQ from Number 51 โ 100                   Answer key: PART 2
PART 3: MCQ from Number 101 โ 150                 Answer key: PART 3
PART 4: MCQ from Number 151 โ 200                 Answer key: PART 4
PART 5: MCQ from Number 201 โ 250                 Answer key: PART 5
PART 6: MCQ from Number 251 โ 300                  Answer key: PART 6
PART 7: MCQ from Number 301 โ 350                  Answer key: included
PART 8: MCQ from Number 351 โ 400                  Answer key: included
PART 9: MCQ from Number 401 โ 450                  Answer key: included
PART 10: MCQ from Number 451 โ 500                 Answer key: included

### Complete List of MCQ in Electronics Engineering per topic

P inoyBIX educates thousands of reviewers and students a day in preparation for their board examinations. Also provides professionals with materials for their lectures and practice exams. Help me go forward with the same spirit.

โWill you subscribe today via YOUTUBE?โ

Subscribe

• Full Content Access Exclusive to Premium members

## PINOYBIX FREEBIES FOR PREMIUM MEMBERSHIP:

• CIVIL ENGINEERING REVIEWER
• CIVIL SERVICE EXAM REVIEWER
• CRIMINOLOGY REVIEWER
• ELECTRONICS ENGINEERING REVIEWER (ECE/ECT)
• ELECTRICAL ENGINEERING & RME REVIEWER
• FIRE OFFICER EXAMINATION REVIEWER
• LET REVIEWER
• MASTER PLUMBER REVIEWER
• MECHANICAL ENGINEERING REVIEWER
• NAPOLCOM REVIEWER

## FOR A LIMITED TIME

If you subscribe for PREMIUM today!