## electrical

### Electrostatics and Capacitance MCQ With Answers Page - 4

1.
 A capacitor consists of two A Ceramic plates and one mica disc B Insulator separated by dielectric C Silver-coated insulators D Conductors separated by an insulator Answer : D Explanation :
2.
3.
 Dielectric strength of a material depends on A Moisture contains B Temperature C Thickness D All of the above Answer : D Explanation :
4.
 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 D Its molecular structure will get changed Answer : C Explanation :
5.
 Its molecular structure will get changed A Paraffin wax B Quartz C Glass D Air Answer : D Explanation :
6.
 1 volt/meter is same as A 1meter/coulomb B 1 newton meter C 1 newton/meter D 1 joule/coulomb Answer : C Explanation :
7.
 One volt is same as A 1 joule / coulomb B 1 coulomb/joule C One coulomb D One joule Answer : A Explanation :
8.
 The capacitance between two plates increase with A Shorter plate area and higher applied voltage B Shorter plate area and shorter distance between them C Larger plate area, longer distance between plates and higher applied voltage D Larger plate area and shorter distance between plates Answer : D Explanation :
9.
 The capacitance c is charged through a resistance R. the time constant of the charging circuit is given by A C/R B 1/RC C RC D R/C Answer : C Explanation :
10.
 The bridge used for the measurement the value of the capacitance is A Wein’s  bridge B Wheastone bridge C Schering bridge D Hay’s bridge Answer : C Explanation :
11.
 A capacitor of 80 µF is charged to a p.d of 250 v. the charge acquired by it is A 0.02 C B 0.2 C C 0.3 C D 0.4 C Answer : A Explanation :
12.
 If an ohm meter reading immediately goes practically to zero and stays there, capacitor is A Charged B Short-circuited C Lossy D Satisfactory Answer : B Explanation :
13.
 A capacitance of 1 µF equals to A 10-12 F B 10-8 F C 10-6 F D 10-4 F Answer : C Explanation :
14.
 Voltage applied across a dielectric produces an electrostatic fields 50 times greater than air. The dielectric constant of the dielectric will be A 5 B 10 C 20 D 50 Answer : D Explanation :
15.
 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 Explanation :
16.
 An uncharged conductor is placed near a charged conductor, then A The uncharged conductor gets charged by conduction B The uncharged conductor gets charged by induction and then attracted towards the charging body C The uncharged conductor is attracted first and then charged by induction D It remains as such Answer : B Explanation :
17.
 The presence of uncharged conductor near a charged one increases the A Charge of the charged conductor B Capacity of the charged conductor C Potential of the charged conductor D All of the above Answer : B Explanation :
18.
 Paper condenser is A Always polarised B Usually of fixed value C Electrolytic condenser D A variable condenser Answer : B Explanation :
19.
 For a good 0.05 µF capacitor ohmmeter reading should A Show low resistance momentarily and back off to a very high resistance B Show high resistance momentarily and then a very low resistance. C Go quickly to 50 ohms approximately and remains there D Not move at all Answer : A Explanation :
20.
 The ohm-meter reading of a short-circuited capacitor is A Infinity B Few kilo ohms C Few mega ohms D Zero Answer : D Explanation :
21.
 Which of the following capacitor preferred for high frequency circuits? A Air capacitor B Electrolytic capacitor C Mica capacitor D None of the above Answer : C Explanation :
22.
 An electrolytic capacitor is generally made to provide A Low capacitance B Fixed capacitance C Variable capacitance D Large value of capacitance Answer : D Explanation :
23.
 In order to remove static electricity from machinery A Construct insulated cabins B Insulate the machinery C Ground the framework D Humidify the surrounding Answer : C Explanation :
24.
 If a third equal and similar charge is placed between two equal and similar charges, then this third charge will be 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 Explanation :
25.
 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 Explanation :
26.
 The minimum value of potential gradient in a cable occurs in A Insulation B Conductor C Outer sheath D Uniformly all over Answer : A Explanation :
27.
 Dielectric strength of medium A Increase with rise in temperature B Increase with moisture content C Is same for all insulating materials D None of the above Answer : D Explanation :
28.
 A charge which when placed in vacuum from an equal and similar charge repels with a force of 9 x 103 N, is known as A Milli-coulomb B Micro-coulomb C Coulombs D Pico-coulomb Answer : B Explanation :
29.
 Dielectric strength of medium is usually expressed in A J/mm B C/m² C kV/mm D N/mm Answer : C Explanation :
30.
 Which of the following medium will have highest value of relative permittivity? A Water B Glass C Mica D Paper Answer : A Explanation :
31.
 “The force of attraction or repulsion between two charges Q1 and Q2 at a distance d meters apart is proportional to the product of charges and inversely proportional to the square of the distance between the two charges”. The above statement is associated with A Maxwell’s law B Lenz’s law C Coulomb’s law D Faraday’s law Answer : C Explanation :
32.
 Which is the most superior dielectric out of the following? A Air B Glass C Bakelite D Paper Answer : C Explanation :
33.
 When a dielectric is placed in an electric field, the field strength A Decreases B Increases C Reduces to zero D Remain unchanged Answer : A Explanation :
34.
 To prevent the generation of static charges on a rubber or flat leather A Surface is moistened B Conductive dressing is done C Oil compound dressing is done D Talcum powder is sprayed on the surface Answer : B Explanation :
35.
 A capacitor having a capacitance of 40µF is connected across 250 V D.C source. The charging current will be least A When capacitor is fully charged B When capacitor is half charged C When capacitor is almost 25% charged D Initially Answer : A Explanation :
36.
 A variable capacitance is one whose capacitance A Changes with temperature B Changes with time C Can be changed manually or by mechanically means D Changes with voltage Answer : C Explanation :
37.
 In case of lossy capacitor, its series equivalent resistance value will be A Large B Small C Very small D Negligible Answer : A Explanation :
38.
 Which of the following capacitor is preferred in case of single phase motor? A Mica capacitor B Paper capacitor C Electrolytic capacitor D Ceramic capacitor Answer : C Explanation :
39.
 A capacitance is a circuit component that opposes the change in the circuit A Current B Voltage C Impedance D None of the above Answer : B Explanation :
40.
 If Q and C be the charge and capacity of a condenser, then the enrgy store in the capacitor is given by A ½ C2Q B ½ Q²/C2 C ½ Q²/C D ½ C2Q² Answer : C Explanation :