McqMate
| 201. |
Which capacitors relatively costly? |
| A. | electrolyte capacitor |
| B. | mica capacitor |
| C. | air capacitor |
| D. | glass capacitor |
| Answer» B. mica capacitor | |
| 202. |
capacitors have a high leakage voltage. |
| A. | electrolyte capacitor |
| B. | variable capacitor |
| C. | "c) air capacitor |
| D. | polyester capacitor |
| Answer» D. polyester capacitor | |
| 203. |
The force between two charges is 120 N. If the distance between the charges is doubled, the force will be |
| A. | 60 n |
| B. | 30 n |
| C. | 40 n |
| D. | 15 n |
| Answer» B. 30 n | |
| 204. |
The electric field intensity at a point situated 4 metres from a point charge is 200 N/C. If the distance is reduced to 2 metres, the field intensity will be |
| A. | 400 n/c |
| B. | 600 n/c |
| C. | 800 n/c |
| D. | 1200 n/c |
| Answer» C. 800 n/c | |
| 205. |
The lines of force due to charged particles are |
| A. | always straight |
| B. | always curved |
| C. | sometimes curved |
| D. | none of the above |
| Answer» B. always curved | |
| 206. |
The electric field at a point situated at a distance d from straight charged conductor is |
| A. | proportional to d |
| B. | inversely proportional to d |
| C. | inversely proportional to d |
| D. | none of the above |
| Answer» B. inversely proportional to d | |
| 207. |
The direction of electric field due +0 positive charge is . |
| A. | away from the charge |
| B. | towards the charge |
| C. | both (a) and (6) |
| D. | none of the above |
| Answer» A. away from the charge | |
| 208. |
A field line and an equipotential surface are |
| A. | always parallel |
| B. | always at 90° |
| C. | inclined at any angle 0 |
| D. | none of the above |
| Answer» B. always at 90° | |
| 209. |
The ability of charged bodies to exert force on 6ne another is attributed to the existence of |
| A. | electrons |
| B. | protons |
| C. | neutrons |
| D. | electric field |
| Answer» D. electric field | |
| 210. |
If the sheet of a bakelite is inserted between the plates of an air capacitor, the capacitance will |
| A. | decrease |
| B. | increase |
| C. | remains unchanged |
| D. | become zero |
| Answer» B. increase | |
| 211. |
A capacitor stores 0.24 coulombs at 10 volts. Its capacitance is |
| A. | 0.024 f |
| B. | 0.12 f |
| C. | 0.6 f |
| D. | 0.8 f |
| Answer» A. 0.024 f | |
| 212. |
For making a capacitor, it is better to select a dielectric having |
| A. | low permittivity |
| B. | high permittivity |
| C. | permittivity same as that of air |
| D. | permittivity slightly more than that of air |
| Answer» B. high permittivity | |
| 213. |
The units of capacitance are |
| A. | volts/coulomb |
| B. | coulombs/volt |
| C. | ohms |
| D. | henry/wb |
| Answer» B. coulombs/volt | |
| 214. |
If three 10 uF capacitors are connected in parallel, the net cararitance is |
| A. | 20 uf |
| B. | 30 ue |
| C. | 40 uf |
| D. | 50 uf |
| Answer» B. 30 ue | |
| 215. |
A dielectric material must be |
| A. | resistor |
| B. | insulator |
| C. | good conductor |
| D. | semi conductor |
| Answer» B. insulator | |
| 216. |
Which of the following is not a vector ? |
| A. | linear momentum |
| B. | angular momentum |
| C. | electric field |
| D. | electric potential |
| Answer» B. angular momentum | |
| 217. |
Two plates of a parallel plate capacitor after being charged from a constant voltage source are separated apart by means of insulated handles, then the |
| A. | voltage across the plates increases |
| B. | voltage across the plates decreases |
| C. | charge on the capacitor decreases |
| D. | charge on the capacitor increases |
| Answer» B. voltage across the plates decreases | |
| 218. |
If A.C. voltage is applied to capacitive circuit, the alternating current can flow in the circuit because |
| A. | varying voltage produces the charg¬ing and dicharging currents |
| B. | of high peak value |
| C. | charging current can flow |
| D. | discharge current can flow |
| Answer» A. varying voltage produces the charg¬ing and dicharging currents | |
| 219. |
The dissipation factor of a good dielectric is of the order of |
| A. | 0.0002 |
| B. | 0.002 |
| C. | 0.02 |
| D. | 0.2 |
| Answer» A. 0.0002 | |
| 220. |
Three capacitors each of the capacity C are given. The resultant capacity 2/3 C can be obtained by using them |
| A. | all in series |
| B. | all in parallel |
| C. | two in parallel and third in series with this combination |
| D. | two in series and third in parallel across this combination |
| Answer» C. two in parallel and third in series with this combination | |
| 221. |
For which of the following parameter variation, the capacitance of the capacitor remains unaffected ? |
| A. | distance between plates |
| B. | area of the plates |
| C. | nature of dielectric |
| D. | thickness of the plates |
| Answer» D. thickness of the plates | |
| 222. |
Which of the following statement is true ? |
| A. | the current in the discharging capacitor grows linearly |
| B. | the current in the dicharging capacitor grows exponentially |
| C. | the current in the discharging capacitor decays exponentially |
| D. | the current in the discharging capacitor decreases constantly |
| Answer» B. the current in the dicharging capacitor grows exponentially | |
| 223. |
Which of the following expression is correct for electric field strength ? |
| A. | E = D/E |
| B. | E = D2/t |
| C. | E = jtD |
| D. | E = nD2 |
| Answer» A. E = D/E | |
| 224. |
In a capacitor the electric charge is stored in |
| A. | metal plates |
| B. | dielectric |
| C. | both (a) and (6) |
| D. | none of the above |
| Answer» B. dielectric | |
| 225. |
Which of the following materials has the highest value of dielectric constant? |
| A. | glass |
| B. | vacuum |
| C. | ceramics |
| D. | oil |
| Answer» C. ceramics | |
| 226. |
Which of the following capacitors will have the least variation ? |
| A. | paper capacitor |
| B. | ceramic capacitor |
| C. | silver plated mica capacitor |
| D. | none of the above |
| Answer» C. silver plated mica capacitor | |
| 227. |
Which of the following statements is incorrect ? |
| A. | the leakage resistance of ceramic capacitors is generally high |
| B. | the stored energy in a capacitor decreases with reduction in value of capacitance |
| C. | the stored energy in a capacitor increases with applied voltage |
| D. | a wire cable has distributed capacitance between the conductors |
| Answer» B. the stored energy in a capacitor decreases with reduction in value of capacitance | |
| 228. |
Which of the following capacitors has relatively shorter shelf life ? |
| A. | mica capacitor |
| B. | electrolytic capacitor |
| C. | ceramic capacitor |
| D. | paper capacitor |
| Answer» B. electrolytic capacitor | |
| 229. |
In the case of a lossy capacitor, its series equivalent resistance value will be |
| A. | small |
| B. | very small |
| C. | large |
| D. | zero |
| Answer» C. large | |
| 230. |
In a capacitive circuit |
| A. | a steady value of applied voltage causes discharge |
| B. | an increase in applied voltage makes a capacitor charge |
| C. | decrease in applied voltage makes a capacitor charge |
| D. | none of the above |
| Answer» B. an increase in applied voltage makes a capacitor charge | |
| 231. |
When a dielectric slab is introduced in a parallel plate capacitor, the potential difference between plates will |
| A. | remain uncharged |
| B. | decrease |
| C. | increase |
| D. | become zero |
| Answer» B. decrease | |
| 232. |
Capacitance increases with |
| A. | increase in plate area and decrease in distance between the plates |
| B. | increase in plate area and distance between the plates |
| C. | decrease in plate area and value of applied voltage |
| D. | reduction in plate area and distance between the plates |
| Answer» A. increase in plate area and decrease in distance between the plates | |
| 233. |
A capacitor consists of |
| A. | two insulators separated by a con¬ductor |
| B. | two conductors separated by an in¬sulator |
| C. | two insulators only |
| D. | two conductors only |
| Answer» B. two conductors separated by an in¬sulator | |
| 234. |
A paper capacitor is usually available in the form of |
| A. | tubes |
| B. | rolled foil |
| C. | disc |
| D. | meshed plates |
| Answer» B. rolled foil | |
| 235. |
Air capacitors are generally available in the range |
| A. | 10 to 400 pf |
| B. | 1 to 20 pf |
| C. | 100 to 900 pf |
| D. | 20 to 100 pf |
| Answer» A. 10 to 400 pf | |
| 236. |
The unit of capacitance is |
| A. | henry |
| B. | ohm |
| C. | farad |
| D. | farad/m |
| Answer» C. farad | |
| 237. |
A capacitor in a circuit became hot and ultimately exploded due to wrong con¬nections, which type of capacitor it could be ? |
| A. | paper capacitor |
| B. | ceramic capacitor |
| C. | electrolytic capacitor |
| D. | any-of the above |
| Answer» C. electrolytic capacitor | |
| 238. |
Energy stored in the electric field of a capacitor C when charged from a D.C source of voltage V is equal to joules |
| A. | cv2 |
| B. | c2v |
| C. | cv2 |
| D. | cv |
| Answer» A. cv2 | |
| 239. |
Electric field intensity is a quantity |
| A. | scalar |
| B. | vector |
| C. | both (a) and (6) |
| D. | none of the above |
| Answer» B. vector | |
| 240. |
When 4 volts e.m.f. is applied across a 1 farad capacitor, it will store energy of |
| A. | 2 joules |
| B. | 4 joules |
| C. | 6 joules |
| D. | 8 joules |
| Answer» D. 8 joules | |
| 241. |
The capacitor preferred for high frequency circuits is |
| A. | air capacitor |
| B. | mica capacitor |
| C. | electrolytic capacitor |
| D. | none of the above |
| Answer» B. mica capacitor | |
| 242. |
The capacity of capacitor bank used in power factor correction is expressed in terms of |
| A. | kw |
| B. | kva |
| C. | kvar |
| D. | volts |
| Answer» C. kvar | |
| 243. |
While testing a capacitor with ohm-metre, if the capacitor shows charging, but the final resistance reading is appreciably less than normal, it can be concluded that the capacitor is |
| A. | short-circuited |
| B. | open circuited |
| C. | alright |
| D. | leaky |
| Answer» D. leaky | |
| 244. |
If a 6 (iF capacitor is charged to 200 V, the charge in coulombs will be |
| A. | 800 uc |
| B. | 900 uc |
| C. | 1200 uc |
| D. | 1600 uc |
| Answer» C. 1200 uc | |
| 245. |
Which capacitor will be physically smaller for the same ratings ? |
| A. | ceramic capacitor |
| B. | paper capacitor |
| C. | both will be of equal size |
| D. | none of the above |
| Answer» A. ceramic capacitor | |
| 246. |
What is the value of capacitance that must be connected in parallel with 50 pF condenser to make an equivalent capacitance of 150 pF ? |
| A. | 50 pf |
| B. | 100 pf |
| C. | 150 pf |
| D. | 200 pf |
| Answer» B. 100 pf | |
| 247. |
A mica capacitor and a ceramic capacitor both have the same physical dimensions. Which will have more value of capacitance ? |
| A. | ceramic capacitor |
| B. | mica capacitor |
| C. | both will have identical value of capacitance |
| D. | it depends on applied voltage |
| Answer» A. ceramic capacitor | |
| 248. |
Which of the following material has least value of dielectric constant ? |
| A. | ceramics |
| B. | oil |
| C. | glass |
| D. | paper |
| Answer» B. oil | |
| 249. |
Which of the following capacitors will have the least value of breakdown voltage ? |
| A. | mica |
| B. | paper |
| C. | ceramic |
| D. | electrolytic |
| Answer» D. electrolytic | |
| 250. |
Dielectric constant for mica is nearly |
| A. | 200 |
| B. | 100 |
| C. | 3 to 8 |
| D. | 1 to 2 |
| Answer» C. 3 to 8 | |
| 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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