MCQ in Electricity and Magnetism Fundamentals Part 5 | ECE Board Exam

This is the Multiple Choice Questions Part 5 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 5 of the Series

Choose the letter of the best answer in each questions.

201. Core materials of a good relay have _____________ hysteresis loop.

A. large

B. narrow

C. very large

D. very narrow

202. The magnetic materials should have a large hysteresis loss for one of the following applications.

A. Transformers

B. AC motors

C. Permanent Magnets

D. DC generators

203. If the magnetic material is located within a coil through which alternating current (60 Hz frequency) flows, then __________ hysteresis loops will be formed every second.

A. 60

B. 120

C. 30

D. 180

204. There are how many compounds available in nature?

A. 105

B. 1000

C. 300,000

D. Unlimited

205. Hysteresis is a phenomenon of ______________ in a magnetic circuit.

A. setting up constant flux

B. lagging of H behind B

C. lagging B behind H

D. leading B ahead H

206. What is the measure of the density and sign of the electric charge at a point relative to that at some time?

A. Electric potential

B. Electric charge

C. Electric current

D. Electric intensity

207. __________ is a substance of whose molecules consist of the same kind of atom.

A. Mixture

B. Compound

C. Element

D. Isotope

208. Hipernik is an alloy containing __________ iron and __________ nickel.

A. 40% ; 60%

B. 60% ; 40%

C. 50% ; 50%

D. 70% ; 30%

209. The mass of proton is ____________ the mass of an electron.

A. equal to

B. about 1837 times

C. less than

D. 200 times

210. What is the maximum number of electrons that can be accommodated in the last orbit of an atom?

A. 4

B. 2

C. 8

D. 18

211. The electrons in the last orbit of an atom are called ____________ electrons.

A. free

B. valence

C. bound

D. thermionic

212. If the number of valence electrons of an atom is less than 4, the substance is called

A. a conductor

B. a semiconductor

C. an insulator

D. a superconductor

213. If the number of valence electrons of an atom is more than 4, the substance is called

A. a semiconductor

B. a conductor

C. an insulator

D. a semi-insulator

214. If the number of valence electrons of an atom is exactly 4, then the substance is called

A. a semiconductor

B. a conductor

C. an insulator

D. a cryogenic conductor

215. If the number of valence electrons of an atom is less than 4, then the substance is probably

A. a metal

B. an insulator

C. a non-metal

D. a semiconductor

216. One coulomb of charge consists of ____________ electrons.

A. 624 × 10^16

B. 62.4 × 10^16

C. 6.24 × 10^16

D. 0.624 × 10^16

217. A one cubic cm of copper has how many free electrons at room temperature?

A. 80 × 10^18

B. 8.5 × 10^22

C. 20 × 10^10

D. 50 × 10^20

218. Electronic current in a wire is the flow of ____________ electrons.

A. free

B. valence

C. bound

D. loose

219. Electromotive force in a circuit

A. causes free electrons to flow

B. increases the circuit resistance

C. maintains circuit resistance

D. is needed to make the circuit complete

220. The resistance of a material is ____________ its area of cross-section.

A. directly proportional

B. independent of

C. inversely proportional to

D. equal to

221. If the length and area of cross-section of a wire are doubled, then its resistance

A. becomes four times

B. becomes sixteen times

C. remains the same

D. becomes two times

222. A length of wire has a resistance of 10 ohms. What is the resistance of a wire of the same material three times as long and twice the cross-sectional area?

A. 30 ohms

B. 20 ohms

C. 15 ohms

D. 7 ohms

223. What is the SI unit of specific resistance or resistivity?

A. Ohm-circular mil per inch

B. Ohm-circular mil per foot

C. Ohm-m

D. Ohm-cm

224. The resistivity of a conductor _____________ with an increase in temperature.

A. increases

B. decreases

C. remains the same

D. becomes zero

225. What is the SI unit of conductance?

A. Siemens

B. Mhos

C. Ohms

D. 1/Ohms

226. If the resistance of a material 2 m long and 2 m^2 in area of cross-section is 1.6 × 10^-8 Ω, then its resistivity is

A. 3.2 × 10^-8 Ω-m

B. 1.6 × 10^-8 Ω-m

C. 0.64 × 10^-8 Ω-m

D. 0.16 × 10^-8 Ω-m

227. What is the SI unit of conductivity?

A. Ohms/m

B. Ohms-m

C. Siemens-m

D. Siemens/m

228. The temperature coefficient of resistance of conductors is

A. positive

B. zero

C. negative

D. infinite

229. The temperature coefficient of resistance of semiconductors is

A. positive

B. zero

C. negative

D. infinite

230. What determines the value of the temperature coefficient of resistance of a material?

A. length

B. cross-sectional area

C. volume

D. nature and temperature

231. The temperature coefficient of resistance of a conductor ______________ with an increase in temperature.

A. increases

B. decreases

C. remains the same

D. becomes negative

232. The temperature coefficient of resistance of insulators is

A. zero

B. negative

C. positive

D. infinite

233. The temperature coefficient of resistance of eureka is

A. positive

B. negative

C. almost zero

D. infinite

234. If the value of α0 a conductor is 1/234 per oC, then the value of α18 is

A. 1/218 per °C

B. 1/252 per °C

C. 1/272 per °C

D. 1/273 per °C

235. If the value of α25 a conductor is 1/255 per °C, then the value of α20 is

A. 1/300 per °C

B. 1/250 per °C

C. 1/230 per °C

D. 1/260 per °C

236. If the value of α25 of a conductor is 1/230 per °C, then the value of α0 is

A. 1/180 per °C

B. 1/150 per °C

C. 1/280 per °C

D. 1/230 per °C

237. Ohm’s law cannot be applied to which material?

A. Copper

B. Silver

C. Silicon carbide

D. Aluminum

238. What is the practical unit of electrical energy?

A. Watt

B. Kilowatt-hour

C. Kilowatt-second

D. Megawat-hour

239. A 200-watt lamp working for 24 hours will consume approximately ____________ units.

A. 50

B. 5

C. 24

D. 0.5

240. The hot resistance of an incandescent lamp is about _____________ its cold resistance.

A. 10 times

B. 100 times

C. 5 times

D. 50 times

241. Under ordinary conditions, a body is considered

A. positively charged

B. neutral

C. negatively charged

D. stable

242. A positively charged body has

A. deficit of electrons

B. excess of neutrons

C. excess of electrons

D. deficit of protons

243. A negatively charge body has

A. deficit of electrons

B. excess of protons

C. excess of electrons

D. deficit of neutrons

244. This paper does not exhibit electricity because it contains the same number of

A. protons and electrons

B. neutrons and electrons

C. neutrons and positrons

D. atoms

245. What is the value of the absolute permittivity of air?

A. 8.854 μF/m

B. 8.854 × 10^-12 mF/m

C. 8.854 × 10^-12 F/m

D. 8.854 × 10^-12 μF/m

246. What is the relative permittivity of air?

A. 0

B. 1

C. 8.854 × 10^-12

D. 4π × 10^-7

247. If two similar charges 1 coulomb each are placed 1 m apart in air, then the force of repulsion is

A.8 × 10^6 N

B. 9 × 10^9 N

C. 10^6 N

D. 5 × 10^6 N

248. If the relative permittivity of a material is 10, then its permittivity is

A. 4π × 10^-7 F/m

B. 4π × 10^-6 F/m

C. 8.854 × 10^-11 F/m

D. 8.854 × 10^-12 F/m

249. The force between two charges placed a given distance apart _____________ as the relative permittivity of the medium is increased.

A. increases

B. decreases

C. remains unchanged

D. becomes infinite

250. What is another name for relative permittivity?

A. Dielectric strength

B. Electric intensity

C. Potential gradient

D. Dielectric constant

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