201. Which of the following materials exhibits both magnetic and electrical properties?
A) Ferrites
B) Copper
C) Glass
D) Graphite
Ans: A
202. The domain theory of magnetism was proposed by
A) Maxwell
B) Weiss
C) Faraday
D) Tesla
Ans: B
203. In semiconductors, current conduction takes place due to
A) Free electrons only
B) Holes only
C) Free electrons and holes
D) Ions
Ans: C
204. The relaxation time in metals depends on
A) Temperature
B) Impurities
C) Lattice vibration
D) All of the above
Ans: D
205. The dielectric constant of water is approximately
A) 1
B) 10
C) 80
D) 100
Ans: C
206. Which of the following has a negative temperature coefficient of resistance?
A) Semiconductor
B) Metal
C) Alloy
D) Electrolyte
Ans: A
207. The mobility of electrons in a semiconductor decreases with
A) Increase in temperature
B) Decrease in temperature
C) Increase in doping
D) Increase in electric field
Ans: A
208. Ferrimagnetism is exhibited by
A) Ferrites
B) Nickel
C) Cobalt
D) Iron
Ans: A
209. In a pure semiconductor at absolute zero, the valence band is
A) Empty
B) Half-filled
C) Completely filled
D) Overlapped with conduction band
Ans: C
210. The Fermi level in intrinsic semiconductor lies
A) Close to conduction band
B) Close to valence band
C) Midway between conduction and valence band
D) At conduction band
Ans: C
211. The resistivity of intrinsic semiconductor decreases with
A) Increase in temperature
B) Decrease in temperature
C) Remains constant
D) None
Ans: A
212. Which of the following is a magnetic insulator?
A) Ferrite
B) Iron
C) Nickel
D) Cobalt
Ans: A
213. Dielectric loss occurs due to
A) Leakage current
B) Atomic polarization
C) Lag of polarization behind electric field
D) None
Ans: C
214. The atomic structure of metals is generally
A) Amorphous
B) Crystalline
C) Polycrystalline
D) None
Ans: B
215. The Hall effect is used to determine
A) Carrier type
B) Carrier density
C) Mobility
D) All of these
Ans: D
216. The resistivity of carbon is about
A) Ω-m
B) Ω-m
C) Ω-m
D) Ω-m
Ans: D
217. Which of the following materials can be magnetized permanently?
A) Soft iron
B) Hard steel
C) Silicon steel
D) Ferrite
Ans: B
218. The energy gap of silicon is
A) 0.7 eV
B) 1.1 eV
C) 1.5 eV
D) 3.0 eV
Ans: B
219. The main function of carbon in a carbon resistor is to
A) Provide strength
B) Provide resistivity
C) Provide conduction path
D) Improve insulation
Ans: B
220. The material used for capacitor dielectric in high-voltage applications is
A) Paper
B) Mica
C) Air
D) Plastic
Ans: B
221. Paramagnetic materials have susceptibility
A) > 0
B) < 0
C) = 0
D) Infinite
Ans: A
222. Magnetic moment is measured in
A) Weber
B) Ampere-meter²
C) Tesla
D) Henry
Ans: B
223. The magnetic flux density in a solenoid is proportional to
A) Current
B) Number of turns per unit length
C) Permeability
D) All of these
Ans: D
224. The conductivity of semiconductors increases with
A) Increase in temperature
B) Decrease in temperature
C) Decrease in carrier concentration
D) None
Ans: A
225. A material with partially filled conduction band is
A) Insulator
B) Conductor
C) Semiconductor
D) Dielectric
Ans: B
226. Ferroelectric materials are characterized by
A) Spontaneous polarization
B) Magnetic domain
C) High conductivity
D) None
Ans: A
227. Example of ferroelectric material is
A) BaTiO₃
B) SiO₂
C) ZnO
D) Fe₂O₃
Ans: A
228. The drift velocity of electrons depends on
A) Mobility
B) Electric field
C) Charge
D) Both A and B
Ans: D
229. A piezoelectric crystal generates voltage when subjected to
A) Heat
B) Mechanical stress
C) Electric field
D) Magnetic field
Ans: B
230. A magnetic circuit is analogous to
A) Electric circuit
B) Thermal circuit
C) Both
D) None
Ans: A
231. The best material for making thermocouple junctions is
A) Dissimilar metals
B) Similar metals
C) Alloys
D) Insulators
Ans: A
232. The resistivity of alloys is generally
A) Higher than pure metals
B) Lower than pure metals
C) Same
D) Negligible
Ans: A
233. Which of the following has highest permeability?
A) Air
B) Iron
C) Copper
D) Manganese
Ans: B
234. A dielectric material is characterized by
A) High conductivity
B) Polarization property
C) High resistivity
D) Both B and C
Ans: D
235. The remanence of a material represents
A) Residual magnetism
B) Magnetic reluctance
C) Permeability
D) Coercivity
Ans: A
236. Coercivity is the measure of
A) Energy loss
B) Retentivity
C) Demagnetizing force
D) Magnetic moment
Ans: C
237. The resistivity of intrinsic semiconductor at 0 K is
A) Zero
B) Infinite
C) Constant
D) Unpredictable
Ans: B
238. Which type of materials are best suited for transformer cores?
A) Soft magnetic
B) Hard magnetic
C) Non-magnetic
D) Superconducting
Ans: A
239. The electron mobility in semiconductors decreases when
A) Temperature increases
B) Temperature decreases
C) Electric field decreases
D) Doping decreases
Ans: A
240. The piezoelectric effect is observed in
A) Quartz
B) Copper
C) Silicon
D) Iron
Ans: A
241. The atomic number of silicon is
A) 14
B) 32
C) 28
D) 12
Ans: A
242. Diamagnetic materials are repelled by
A) Magnetic field
B) Electric field
C) Both
D) None
Ans: A
243. Electrical conductivity in electrolytes is due to
A) Electrons
B) Ions
C) Holes
D) None
Ans: B
244. The resistivity of pure metals is mainly due to
A) Lattice vibrations
B) Impurities
C) Defects
D) Temperature
Ans: A
245. The most important property for a heating element material is
A) High resistivity and high melting point
B) Low resistivity
C) Magnetic
D) Ductility
Ans: A
246. Ferromagnetism disappears above
A) Curie temperature
B) Room temperature
C) Melting point
D) Boiling point
Ans: A
247. Which of the following is a high resistivity material?
A) Nichrome
B) Silver
C) Aluminum
D) Gold
Ans: A
248. Eddy current loss is minimized by
A) Laminating the core
B) Using solid core
C) Using copper
D) Increasing thickness
Ans: A
249. The dielectric constant of mica is approximately
A) 2
B) 6
C) 20
D) 80
Ans: B
250. The conductivity of intrinsic semiconductor is
A) High
B) Low
C) Infinite
D) Zero
Ans: B
251. For N-type semiconductor, majority carriers are
A) Holes
B) Electrons
C) Ions
D) None
Ans: B
252. A perfect diamagnetic material has relative permeability
A) 1
B) < 1
C) > 1
D) Infinite
Ans: B
253. The unit of magnetic susceptibility is
A) Dimensionless
B) Tesla
C) Weber
D) Henry
Ans: A
254. Electrical steel is used in transformers because of
A) Low hysteresis loss
B) High resistivity
C) High permeability
D) All of these
Ans: D
255. A good electrical contact material should have
A) Low resistivity
B) High melting point
C) Resistance to corrosion
D) All of these
Ans: D
256. The polarization in a dielectric is directly proportional to
A) Electric field
B) Permittivity
C) Dipole moment
D) All of these
Ans: D
257. The capacitance of a parallel plate capacitor increases with
A) Increase in dielectric constant
B) Decrease in plate spacing
C) Increase in plate area
D) All of these
Ans: D
258. The drift mobility is defined as
A) Velocity per unit field
B) Current per charge
C) Conductivity per field
D) Charge per velocity
Ans: A
259. A semiconductor behaves as an insulator at
A) 0 K
B) Room temperature
C) High temperature
D) Infinite temperature
Ans: A
260. The most commonly used semiconductor material is
A) Silicon
B) Germanium
C) Gallium arsenide
D) Selenium
Ans: A
261. The energy bands in solids are due to
A) Overlapping of atomic orbitals
B) Crystal defects
C) Ionization
D) Excitation
Ans: A
262. The resistivity of metals increases due to
A) Impurities
B) Temperature
C) Dislocations
D) All of these
Ans: D
263. The insulating material for extra high voltage cables is
A) Cross-linked polyethylene (XLPE)
B) PVC
C) Mica
D) Bakelite
Ans: A
264. The superconducting transition temperature is known as
A) Critical temperature
B) Curie temperature
C) Melting point
D) Boiling point
Ans: A
265. The current density is proportional to
A) Electric field
B) Resistivity
C) Voltage
D) Power
Ans: A
266. The Lorentz force acts on
A) Moving charge in magnetic field
B) Stationary charge
C) Neutral atom
D) Static field
Ans: A
267. In ferrites, eddy current losses are small because
A) They have high resistivity
B) They are metallic
C) They are ferromagnetic
D) They are non-magnetic
Ans: A
268. The magnetization curve of soft magnetic material is
A) Narrow hysteresis loop
B) Wide hysteresis loop
C) Linear
D) Random
Ans: A
269. The unit of electric polarization is
A) C/m²
B) A/m²
C) H/m²
D) F/m²
Ans: A
270. The main constituent of glass is
A) SiO₂
B) Al₂O₃
C) CaO
D) Na₂O
Ans: A
271. Permanent magnets are made of
A) High coercivity materials
B) Low coercivity materials
C) High conductivity materials
D) Superconductors
Ans: A
272. Electrical insulators have
A) No free electrons
B) Many free electrons
C) Moderate electrons
D) Negative ions only
Ans: A
273. Which of the following has highest breakdown strength?
A) Mica
B) Paper
C) Air
D) Porcelain
Ans: A
274. The energy stored per unit volume in a magnetic field is
A) ½ BH
B) BH
C) ½ μH²
D) None
Ans: A
275. Magnetostriction effect is the change in
A) Dimension due to magnetization
B) Temperature due to magnetization
C) Weight due to field
D) None
Ans: A
276. Electrical conductivity of copper at 20°C is approximately
A) S/m
B) S/m
C) S/m
D) S/m
Ans: A
277. The basic property of a dielectric is
A) Polarization
B) Magnetization
C) Conduction
D) Superconductivity
Ans: A
278. A good insulator must have
A) High dielectric strength
B) High resistivity
C) Low loss angle
D) All of these
Ans: D
279. The unit of dielectric loss angle is
A) Radian
B) Degree
C) Dimensionless
D) Both A and B
Ans: C
280. The polarization mechanism in polar dielectrics is
A) Orientation
B) Electronic
C) Ionic
D) None
Ans: A
281. A magnetic material with large hysteresis loss is suitable for
A) Permanent magnet
B) Transformer core
C) Relay
D) None
Ans: A
282. The specific resistance is independent of
A) Shape and size
B) Temperature
C) Material
D) All
Ans: A
283. Silicon steel contains about
A) 3–4% silicon
B) 1% silicon
C) 6–8% silicon
D) 0.5% silicon
Ans: A
284. The Curie temperature for iron is approximately
A) 770°C
B) 500°C
C) 100°C
D) 300°C
Ans: A
285. The electrical energy stored in a dielectric medium is
A) ½ εE²
B) εE²
C) ½ μH²
D) None
Ans: A
286. The breakdown in a dielectric is due to
A) Excess electric stress
B) Heat
C) Chemical reaction
D) Magnetic field
Ans: A
287. High resistivity materials are used for
A) Heating elements
B) Rheostats
C) Shunts
D) Contacts
Ans: B
288. The main cause of hysteresis loss is
A) Lagging of flux behind magnetizing force
B) Eddy currents
C) Temperature
D) Resistance
Ans: A
289. A non-crystalline solid is called
A) Amorphous
B) Crystalline
C) Polycrystalline
D) None
Ans: A
290. Which is an amorphous material?
A) Glass
B) Iron
C) Copper
D) Silicon
Ans: A
291. Ferromagnetic substances lose their magnetism when
A) Heated beyond Curie temperature
B) Cooled
C) Magnetized
D) Polarized
Ans: A
292. The dielectric strength of vacuum is
A) 30 kV/cm
B) 10 kV/cm
C) 100 kV/cm
D) 3 kV/cm
Ans: A
293. Hysteresis loop area indicates
A) Energy loss per cycle
B) Permeability
C) Coercivity
D) Magnetization
Ans: A
294. Conductivity of semiconductors lies between
A) Conductors and insulators
B) Metals and ceramics
C) Dielectrics and superconductors
D) None
Ans: A
295. A conductor obeys
A) Ohm’s law
B) Kirchhoff’s law
C) Joule’s law
D) Faraday’s law
Ans: A
296. Ferroelectric materials are used in
A) Capacitors
B) Transformers
C) Inductors
D) Resistors
Ans: A
297. Magnetic flux is measured in
A) Weber
B) Tesla
C) Henry
D) Gauss
Ans: A
298. Thermal conductivity of metals is due to
A) Free electrons
B) Lattice vibrations
C) Both A and B
D) None
Ans: A
299. In dielectric heating, the power loss is proportional to
A) Frequency
B) Voltage²
C) Dielectric constant
D) All of these
Ans: D
300. For an ideal insulator, the loss tangent is
A) Zero
B) Infinity
C) Unity
D) Constant
Ans: A
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