McqMate
201. |
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 |
202. |
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 |
203. |
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 |
204. |
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 |
205. |
The direction of electric field due +0 positive charge is . |
A. | away from the charge |
B. | towards the charge |
C. | both (a) and (b) |
D. | none of the above |
Answer» A. away from the charge |
206. |
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° |
207. |
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 |
208. |
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 |
209. |
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 |
210. |
The units of capacitance area |
A. | volts/coulomb |
B. | coulombs/volt |
C. | ohms |
D. | henry/Wb |
Answer» B. coulombs/volt |
211. |
If three 15 uF capacitors are connected in series, the net capacitance is |
A. | 5 uF |
B. | 30 uF |
C. | 45 uF |
D. | 50 uF |
Answer» A. 5 uF |
212. |
If three 10 uF capacitors are connected in parallel, the net capacitance is |
A. | 20 uF |
B. | 30 uE |
C. | 40 uF |
D. | 50 uF |
Answer» B. 30 uE |
213. |
An electrolytic capacitor can be used for |
A. | D.C. only |
B. | AC. only |
C. | both |
D. | C. as well as A.C. |
Answer» A. D.C. only |
214. |
Which of the following is not a vector ? |
A. | Linear momentum |
B. | Angular momentum |
C. | Electric field |
D. | Electric potential |
Answer» B. Angular momentum |
215. |
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 |
216. |
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 |
217. |
Voltage applied across a ceramic dielectric produces an electrolytic field 100 times greater than air. What will be the value of dielectric constant ? |
A. | 50 |
B. | 100 |
C. | 150 |
D. | 200 |
Answer» B. 100 |
218. |
Which of the following statements is correct ? |
A. | Air capacitors have a blackband to indicate the outside foil |
B. | Electrolytic capacitor must be con¬nected in the correct polarity |
C. | Ceramic capacitors must be con¬nected in the correct polarity |
D. | Mica capacitors are available in capacitance value of 1 to 10 pF |
Answer» B. Electrolytic capacitor must be con¬nected in the correct polarity |
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. |
"The total electric flux through any closed surface surrounding charges is equal to the amount oflcharge enclosed". The above statement is associated with |
A. | Coulomb's square law |
B. | Gauss's law |
C. | Maxwell's first law |
D. | Maxwell's second law |
Answer» B. Gauss's law |
221. |
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 |
222. |
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 |
223. |
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 |
224. |
In a capacitor the electric charge is stored in |
A. | metal plates |
B. | dielectric |
C. | both (a) and (b) |
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. |
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 |
231. |
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 |
232. |
A capacitor consists of |
A. | two insulators separated by a conductor |
B. | two conductors separated by an insulator |
C. | two insulators only |
D. | two conductors only |
Answer» B. two conductors separated by an insulator |
233. |
A gang condenser is a |
A. | polarised capacitor |
B. | variable capacitor |
C. | ceramic capacitor |
D. | none of the above |
Answer» B. variable capacitor |
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 charged to 200 V has 2000 (iC of charge. The value of capacitance will be |
A. | 10 F |
B. | 10 uF |
C. | 100 nF |
D. | 1000 uF |
Answer» B. 10 uF |
238. |
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 |
239. |
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. | CV3 |
D. | CV |
Answer» A. CV2 |
240. |
The absolute permittivity of free space is given by |
A. | 8.854 x 1(T9 F/m) |
B. | 8.854 x 1(T10 F/m) |
C. | 8.854 x KT11 F/m |
D. | 8.854 x 10"12 F/m |
Answer» B. 8.854 x 1(T10 F/m) |
241. |
The relative permittivity of free space is given by |
A. | 1 |
B. | 10 |
C. | 100 |
D. | 1000 |
Answer» B. 10 |
242. |
Electric field intensity is a quantity |
A. | scalar |
B. | vector |
C. | both (a) and (b) |
D. | none of the above |
Answer» B. vector |
243. |
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 |
244. |
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 |
245. |
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 |
246. |
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 |
247. |
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 |
248. |
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 |
249. |
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 |
250. |
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 |
251. |
Which of the following material has least value of dielectric constant ? |
A. | Ceramics |
B. | Oil |
C. | Glass |
D. | Paper |
Answer» B. Oil |
252. |
Which of the following capacitors will have the least value of breakdown voltage ? |
A. | Mica |
B. | Paper |
C. | Ceramic |
D. | Electrolytic |
Answer» D. Electrolytic |
253. |
Dielectric constant for mica is nearly |
A. | 200 |
B. | 100 |
C. | 3 to 8 |
D. | 1 to 2 |
Answer» C. 3 to 8 |
254. |
The value of dielectric constant for vacuum is taken as |
A. | zero |
B. | 1 |
C. | 4 |
D. | 10 |
Answer» B. 1 |
255. |
Which of the following capacitors is marked for polarity ? |
A. | Air |
B. | Paper |
C. | Mica |
D. | Electrolytic |
Answer» D. Electrolytic |
256. |
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 |
257. |
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 |
258. |
Paper capacitors usually have a tolerance of |
A. | ± 5% |
B. | ± 10% |
C. | ± 15% |
D. | ± 20% |
Answer» B. ± 10% |
259. |
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 |
260. |
The electrostatic force between two charges of one coulomb each and placed at 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 |
261. |
The units of volume charge density are |
A. | Coulomb/metre |
B. | Coulomb/metre |
C. | Coulomb/metre |
D. | Coulomb/metre |
Answer» C. Coulomb/metre |
262. |
"The surface integral of the normal component of the electric displacement D over any closed surface equals the charge enclosed by the surface". The above statement is associated with |
A. | Gauss's law |
B. | Kirchhoff s law |
C. | Faraday's law |
D. | Lenz's law |
Answer» A. Gauss's law |
263. |
Dielectric strength of mica is |
A. | 10 to 20 kV/mm |
B. | 30 to 50 kV/mm |
C. | 50 to 200 kV/mm |
D. | 300 to 500 kV/mm |
Answer» C. 50 to 200 kV/mm |
264. |
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 |
265. |
capacitors are mainly used for radio frequency tuning. |
A. | Paper |
B. | Air |
C. | Mica |
D. | Electrolytic |
Answer» B. Air |
266. |
capacitors can be used only for D.C. |
A. | Air |
B. | Paper |
C. | Mica |
D. | Electrolytic |
Answer» D. Electrolytic |
267. |
capacitors are used in transistor circuits. |
A. | Ceramic |
B. | Paper |
C. | Air |
D. | Electrolytic |
Answer» A. Ceramic |
268. |
Capacitors are used for audio frequency and radio frequency coupling and tuning. |
A. | Air |
B. | Mica |
C. | Plastic film |
D. | Ceramic |
Answer» B. Mica |
269. |
The inverse of capacitance is called |
A. | reluctance |
B. | conductance |
C. | susceptance |
D. | elastance |
Answer» D. elastance |
270. |
When the dielectric is homogeneous,the potential gradient is |
A. | uniform |
B. | non-uniform |
C. | zero |
D. | any of the above |
Answer» A. uniform |
271. |
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 |
272. |
field is associated with the capacitor. |
A. | Electric |
B. | Magnetic |
C. | Both (a) and (b) |
D. | None of the above |
Answer» A. Electric |
273. |
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 |
274. |
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 |
275. |
Two infinite parallel plates 10 mm apart have maintained between them a potential difference of 100 V. The acceleration of an electron placed between them is |
A. | 0.56 x 1015 m/s2 |
B. | 1.5 x 1015 m/s2 |
C. | 1.6 x 1015 m/s2 |
D. | 1.76 x 1015 m/s2 |
Answer» D. 1.76 x 1015 m/s2 |
276. |
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 |
277. |
The relative permittivity has the following units |
A. | F/m |
B. | m/F |
C. | Wb/m |
D. | no units |
Answer» C. Wb/m |
278. |
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 |
279. |
A unit tube of flux is known as tube |
A. | Newton |
B. | Faraday |
C. | Michale |
D. | None of the above |
Answer» B. Faraday |
280. |
The number of Faraday tubes of flux passing through a surface in an electric field is called |
A. | electric flux |
B. | electric flux density |
C. | magnetic flux density |
D. | electric charge density |
Answer» A. electric flux |
281. |
The unit of electric instensity is |
A. | N/C2 |
B. | Wb/m2 |
C. | N/C |
D. | N2/C |
Answer» B. Wb/m2 |
282. |
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 |
283. |
at a point may be defined as equal to the lines of force passing normally through a unit cross section at that point. |
A. | Electric intensity |
B. | Magnetic flux density |
C. | Electric flux |
D. | None of the above |
Answer» A. Electric intensity |
284. |
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 |
285. |
Electric displacement is a quantity. |
A. | scalar |
B. | vector |
C. | both of the above |
D. | none of the above |
Answer» B. vector |
286. |
at a point is equal to the negative potential gradient at that point. |
A. | Electric intensity |
B. | Electric flux |
C. | Magnetic flux |
D. | Magnetic flux density |
Answer» A. Electric intensity |
287. |
The unit of dielectric strength is given by |
A. | V/m |
B. | V2/m |
C. | m/V |
D. | m/V2 |
Answer» A. V/m |
288. |
Dielectric stregth______with increasing thickness |
A. | increases |
B. | decreases |
C. | remains unaltered |
D. | none of the above |
Answer» B. decreases |
289. |
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 |
290. |
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 |
291. |
A capacitance of 100 f if is connected in series with a resistance of 8000 £2. The time constant of the circuit is |
A. | 0.2 s |
B. | 0.4 |
C. | 0.6 s |
D. | 0.8 s |
Answer» D. 0.8 s |
292. |
In a cable capacitor, voltage gradient is maximum at the surface of the |
A. | earth |
B. | conduction |
C. | sheath |
D. | insulator |
Answer» B. conduction |
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