McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Electrical Engineering .
| 251. |
The value of dielectric constant for vacuum is taken as |
| A. | zero |
| B. | 1 |
| C. | 4 |
| D. | 10 |
| Answer» B. 1 | |
| 252. |
Which of the following capacitors is marked for polarity ? |
| A. | air |
| B. | paper |
| C. | mica |
| D. | electrolytic |
| Answer» D. electrolytic | |
| 253. |
Which of the following capacitors can be used for temperature compensation ? |
| A. | air capacitor |
| B. | ceramic capacitor |
| C. | paper capacitor |
| D. | none of the above |
| Answer» B. ceramic capacitor | |
| 254. |
Which of the following statements is incorrect ? |
| A. | the thinner the dielectric, the more the capacitance and the lower the voltage breakdown rating for a capacitor . |
| B. | a six dot mica capacitor colour coded white, green, black, red and yellow has the capacitance value of 500 pf |
| C. | capacitors in series provide less capacitance but a higher voltage breakdown rating for the combina¬tion |
| D. | a capacitor can store charge be¬cause it has a dielectric between two conductors |
| Answer» B. a six dot mica capacitor colour coded white, green, black, red and yellow has the capacitance value of 500 pf | |
| 255. |
For closer tolerances which of the following capacitors is usually preferred ? |
| A. | paper capacitor |
| B. | mica capacitor |
| C. | ceramic disc capacitor |
| D. | none of the above |
| Answer» B. mica capacitor | |
| 256. |
The electrostatic force between two charges of one coulomb each and placed at a distance of 0.5 m will be |
| A. | 36 x 10fa |
| B. | 36 x 107 n |
| C. | 36 x 108 n |
| D. | 36 x 109 n |
| Answer» D. 36 x 109 n | |
| 257. |
The units of volume charge density are |
| A. | coulomb/metre |
| B. | coulomb/metre |
| C. | coulomb/metre |
| D. | coulomb/metre |
| Answer» C. coulomb/metre | |
| 258. |
The dielectric constant (relative permittivity) of glass is given by |
| A. | 0.1 to 0.4 |
| B. | 0.5 to 1.0 |
| C. | 2.0 to 4.0 |
| D. | 5 to 100 |
| Answer» D. 5 to 100 | |
| 259. |
capacitors are used in transistor circuits. |
| A. | ceramic |
| B. | paper |
| C. | air |
| D. | electrolytic |
| Answer» A. ceramic | |
| 260. |
capacitors are used for audio frequency and radio frequency coupling and tuning. |
| A. | air |
| B. | mica |
| C. | plastic film |
| D. | ceramic |
| Answer» B. mica | |
| 261. |
The inverse of capacitance is called |
| A. | reluctance |
| B. | conductance |
| C. | susceptance |
| D. | elastance |
| Answer» D. elastance | |
| 262. |
When the dielectric is homogeneous,the potential gradient is |
| A. | uniform |
| B. | non-uniform |
| C. | zero |
| D. | any of the above |
| Answer» A. uniform | |
| 263. |
The potential gradient across the material of low permittivity is than across the material of high permittivity. |
| A. | smaller |
| B. | greater |
| C. | both (a) and (b) |
| D. | none of the above |
| Answer» B. greater | |
| 264. |
field is associated with the capacitor. |
| A. | electric |
| B. | magnetic |
| C. | both (a) and (b) |
| D. | none of the above |
| Answer» A. electric | |
| 265. |
A capacitor having capacitance of 5 uF is charged to a potential difference of 10,000 V. The energy stored in the capacitor is |
| A. | 50 joules |
| B. | 150 joules |
| C. | 200 joules |
| D. | 250 joules |
| Answer» D. 250 joules | |
| 266. |
A single core cable used on 33000 V has conductor diameter 10 mm and the in¬ternal diameter of sheath 25 mm. The maximum electrostatic stress in the cable is |
| A. | 62 x 105 v/m |
| B. | 72 x 105 v/m |
| C. | 82 x 105 v/m |
| D. | 92 x 105 v/m |
| Answer» B. 72 x 105 v/m | |
| 267. |
The total deficiency or excess of electrons in a body is known as |
| A. | current |
| B. | voltage |
| C. | potential gradient |
| D. | charge |
| Answer» D. charge | |
| 268. |
The relative permittivity has the following units |
| A. | f/m |
| B. | m/f |
| C. | wb/m |
| D. | no units |
| Answer» C. wb/m | |
| 269. |
The phenomenon of an uncharged body getting charged merely by the nearness of a charged body is known as |
| A. | pholoelectric effect |
| B. | chemical effect |
| C. | magnetic effect |
| D. | induction |
| Answer» D. induction | |
| 270. |
A unit tube of flux is known as tube |
| A. | newton |
| B. | faraday |
| C. | michale |
| D. | none of the above |
| Answer» B. faraday | |
| 271. |
The value of E within the field due to a point charge can be found with the help of |
| A. | faraday\s laws |
| B. | kirchhoff s laws |
| C. | coulomb\s laws |
| D. | none of the above |
| Answer» C. coulomb\s laws | |
| 272. |
Electric intensity at any point in an electric field is equal to the at that point. |
| A. | electric flux |
| B. | magnetic flux density |
| C. | potential gradient |
| D. | none of the above |
| Answer» C. potential gradient | |
| 273. |
Electric displacement is a quantity. |
| A. | scalar |
| B. | vector |
| C. | both of the above |
| D. | none of the above |
| Answer» B. vector | |
| 274. |
The unit of dielectric strength is given by |
| A. | v/m |
| B. | v2/m |
| C. | m/v |
| D. | m/v2 |
| Answer» A. v/m | |
| 275. |
Dielectric strength with increasing thickness |
| A. | increases |
| B. | decreases |
| C. | remains unaltered |
| D. | none of the above |
| Answer» B. decreases | |
| 276. |
The property of a capacitor to store electricity is called its |
| A. | capacitance |
| B. | charge |
| C. | energy |
| D. | none of the above |
| Answer» A. capacitance | |
| 277. |
is that property of a capacitor which delays any change of voltage across it. |
| A. | inductance |
| B. | capacitance |
| C. | potential gradient |
| D. | none of the above |
| Answer» B. capacitance | |
| 278. |
A capacitance of 100 fiF is connected in series with a resistance of 8000 £2. The time constant of the circuit is |
| A. | 0.2 s |
| B. | 0.4 s |
| C. | 0.6 s |
| D. | 0.8 s |
| Answer» D. 0.8 s | |
| 279. |
In a cable capacitor, voltage gradient ismaximum at the surface of the |
| A. | earth |
| B. | conduction |
| C. | sheath |
| D. | insulator |
| Answer» B. conduction | |
| 280. |
The time constant of an R-C circuit is defined as the time during which capacitor charging voltage actually rises to percent of its value. |
| A. | 37, initial |
| B. | 63.2, initial |
| C. | 63.2, final |
| D. | 37, final |
| Answer» C. 63.2, final | |
| 281. |
The time constant and R-C circuit may also be defined as the time during which the charging current falls to percent of its initial maximum value, |
| A. | 37 |
| B. | 42 |
| C. | 63 |
| D. | 73 |
| Answer» A. 37 | |
| 282. |
A capacitor consists of two |
| A. | ceramic plates and one mica disc |
| B. | insulators separated by a dielectric |
| C. | silver-coated insulators |
| D. | conductors separated by an insulator |
| Answer» D. conductors separated by an insulator | |
| 283. |
Permittivity is expressed in |
| A. | farad/sq-m |
| B. | farad/metre |
| C. | weber/metre |
| D. | weber/sq-m |
| Answer» B. farad/metre | |
| 284. |
What will happen to an insulating medium if voltage more than the breakdown voltage is applied on it ? |
| A. | it will become magnetic |
| B. | it will melt |
| C. | it will get punctured or cracked |
| D. | its molecular structure will get changed |
| Answer» C. it will get punctured or cracked | |
| 285. |
Which medium has the least dielectric strength ? |
| A. | paraffin wax |
| B. | quartz |
| C. | glass |
| D. | air |
| Answer» D. air | |
| 286. |
One volt is the same as |
| A. | one joule/coulomb |
| B. | one coulomb/joule |
| C. | one coulomb |
| D. | one joule |
| Answer» A. one joule/coulomb | |
| 287. |
The capacitance C is charged through a resistance R. The time constant of the charging circuit is given by |
| A. | cir |
| B. | 1/rc |
| C. | rc |
| D. | ric |
| Answer» C. rc | |
| 288. |
The bridge used for the measurement of the value of the capacitance is |
| A. | wien\s bridge |
| B. | wheatstone bridge |
| C. | schering bridge |
| D. | hay\s bridge |
| Answer» C. schering bridge | |
| 289. |
If an ohmmeter reading immediately goes practically to zero and stays there, capacitor is |
| A. | charged |
| B. | short-circuited |
| C. | lossy |
| D. | satisfactory |
| Answer» B. short-circuited | |
| 290. |
Out of the following capacitors of identical rating which one will have the smallest dimensions ? |
| A. | aluminium foil capacitor |
| B. | mica capacitor |
| C. | ceramic capacitor |
| D. | paper capacitor |
| Answer» C. ceramic capacitor | |
| 291. |
Mica capacitors are characterised by all of thte following except |
| A. | stable operation |
| B. | accurate value |
| C. | low leakage reactance |
| D. | low losses |
| Answer» C. low leakage reactance | |
| 292. |
A potential of 400 V is applied to a capacitor, the plates of which are 4 mm apart. The strength of electric field is |
| A. | 100 kv/m |
| B. | 10 kv/m |
| C. | 5 kv/m |
| D. | 2 kv/m |
| Answer» A. 100 kv/m | |
| 293. |
The ohmmeter reading for a short circuited capacitor is |
| A. | infinity |
| B. | few kilo ohms |
| C. | few megaahms |
| D. | zero |
| Answer» D. zero | |
| 294. |
Which of the following statements is correct ? |
| A. | mica capacitors are available in capacitance values of 5 to 20 \\if |
| B. | air capapitors have a black band to indicate the outside foil |
| C. | electrolytic capacitors must be connected in correct polarity |
| D. | ceramic capacitors must be con¬nected in correct polarity |
| Answer» C. electrolytic capacitors must be connected in correct polarity | |
| 295. |
Which of the following capacitors preferred for high frequency circuits ? |
| A. | air capacitor |
| B. | electrolytic capacitor |
| C. | mica capacitor |
| D. | none of the above |
| Answer» C. mica capacitor | |
| 296. |
An electrolytic capacitor is generally made to provide |
| A. | low capacitance |
| B. | fixed capacitance |
| C. | variable capacitance |
| D. | large value of capacitance |
| Answer» D. large value of capacitance | |
| 297. |
In order to remove static electricity from machinery |
| A. | construct insulated cabins |
| B. | insulate the machinery |
| C. | ground the framework |
| D. | humidify the surroundings |
| Answer» C. ground the framework | |
| 298. |
If a third equal and similar charge is placed between two equal and similar charges, then this third charge will |
| A. | move out of the field of influence of the two charges |
| B. | remain in stable equilibrium |
| C. | not be in equilibrium |
| D. | be in unstable equilibrium |
| Answer» B. remain in stable equilibrium | |
| 299. |
A region around a stationary electric charge has |
| A. | an electric field |
| B. | a magnetic field |
| C. | both (a) and (b) |
| D. | none of the above |
| Answer» A. an electric field | |
| 300. |
The minimum value of potential gradient in a cable occurs in |
| A. | insulation |
| B. | conductor |
| C. | outer sheath |
| D. | uniformly all over |
| Answer» A. insulation | |
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