209 + Interview Questions in Capacitance And Capacitors in Basic Electrical Engineering Page 2 InterviewSolution

51.	Which capacitors relatively costly?(a) Electrolyte capacitor(b) Mica capacitor(c) Air capacitor(d) Glass capacitorI have been asked this question in an online quiz.My question is taken from Types of Capacitor and Capacitance in division Capacitance and Capacitors of Basic Electrical Engineering
Answer» The correct answer is (B) Mica capacitor To EXPLAIN I would say: Mica capacitors are relatively expensive because it consists EITHER of alternate layers of mica and metal foil CLAMPED tightly together, or of thin films of SILVER on the two sides of a mica sheet. Silver is an expensive metal, hence mica capacitors are expensive.

Discussion

52.	Under normal conditions capacitors have _________(a) Displacement current(b) Conduction current(c) Both conduction and displacement current(d) Neither conduction nor displacement currentI had been asked this question in homework.My enquiry is from Leakage and Conduction Currents in Capacitors topic in division Capacitance and Capacitors of Basic Electrical Engineering
Answer» Correct choice is (a) Displacement current To ELABORATE: Under normal conditions CAPACITORS contain an insulating material called DIELECTRIC sandwiched between the plates of the capacitor. Since insulators can carry only an electric field but not MOVING carriers, therefore NORMALLY a capacitor has displacement current and not conduction current.

Discussion

53.	If the Voltage increases, what happens to dielectric strength?(a) Increases(b) Decreases(c) Remains the same(d) Becomes zeroI had been asked this question by my college director while I was bunking the class.This intriguing question originated from Dielectric Strength in chapter Capacitance and Capacitors of Basic Electrical Engineering
Answer» Correct option is (a) Increases Best EXPLANATION: Dielectric strength is the potential gradient REQUIRED to cause a breakdown in the material. Potential gradient is the ratio of voltage and length. HENCE as potential increases, dielectric strength also increases.

Discussion

54.	The free electrons in practical dielectrics is due to _________(a) There are no free electrons(b) Conductors(c) Impurities(d) Both conductors and impuritiesI have been asked this question in an international level competition.This interesting question is from Leakage and Conduction Currents in Capacitors topic in division Capacitance and Capacitors of Basic Electrical Engineering
Answer» Right answer is (C) Impurities To explain I would say: IDEALLY, DIELECTRICS are INSULATORS and do not contain any free electrons. But no DIELECTRIC is a perfect dielectric, hence the free electrons are due to impurities present in each dielectric.

Discussion

55.	What happens to the force of attraction between the capacitors when the potential difference between the plates decreases?(a) Increases(b) Decreases(c) Remains the same(d) Becomes zeroThis question was posed to me by my school teacher while I was bunking the class.My question is taken from Force of Attraction Between Oppositely Charged Plates in chapter Capacitance and Capacitors of Basic Electrical Engineering
Answer» The correct choice is (B) Decreases Best explanation: The force of ATTRACTION between the two PLATES of the capacitor is directly proportional to the SQUARE of the potential difference between the plates, hence as the potential difference decreases, the force of attraction also decreases.

Discussion

56.	Which among the following is the correct expression for force between the plates of a parallel plate capacitor?(a) F=epsilonA(V/x)^2/2(b) F=epsilonA(V/x)^2/3(c) F=epsilon (V/x)^2/2(d) F=epsilon (V/x)^2/3I had been asked this question in exam.This intriguing question originated from Force of Attraction Between Oppositely Charged Plates topic in portion Capacitance and Capacitors of Basic Electrical Engineering
Answer» RIGHT option is (a) F=epsilonA(V/x)^2/2 The best EXPLANATION: The force is proportional to the square of the potential GRADIENT and the area. HENCE the force F=epsilonA(V/x)^2/2.

Discussion

57.	The type of capacitors used in communication transmitters are?(a) Electrolyte capacitor(b) Variable capacitor(c) Air capacitor(d) Glass capacitorI have been asked this question during an interview.Asked question is from Types of Capacitor and Capacitance topic in portion Capacitance and Capacitors of Basic Electrical Engineering
Answer» Correct option is (b) Variable capacitor Explanation: Variable capacitor is used to TUNE all the circuits to same FREQUENCY i.e. RESONANCE frequency so they are used in communication TRANSMITTERS.

Discussion

58.	Displacement current depends on ___________(a) Moving charges(b) Change in time(c) Both moving charges and change in time(d) Neither moving charges nor change in timeI have been asked this question in an interview.My doubt stems from Displacement Current in a Dielectric in division Capacitance and Capacitors of Basic Electrical Engineering
Answer» The correct choice is (B) Change in time The best explanation: Displacement CURRENT is the current which arises DUE to variations in the FIELD. Hence, it does not depend on the moving charges but it changes with time which causes variation in the field.

Discussion

59.	What happens to the capacitor when the capacitor voltage is equal to the source voltage?(a) The charging phase of the capacitor is over(b) The discharging phase of the capacitor is over(c) The capacitor is switched off(d) The capacitor is switched onThis question was posed to me during an interview.My question is based upon Charging and Discharging Currents in division Capacitance and Capacitors of Basic Electrical Engineering
Answer» The correct choice is (c) The CAPACITOR is switched off Best EXPLANATION: When the capacitor voltage is equal to the source voltage, it means that all the charges have moved from one plate of the capacitor to the other. Hence the capacitor is fully charged and we say it GETS switched off.

Discussion

60.	The simplest kind of capacitor is ________(a) Ceramic capacitor(b) Electrolyte capacitor(c) Tuning capacitor(d) Paper capacitorThis question was addressed to me by my college director while I was bunking the class.I'd like to ask this question from Types of Capacitor and Capacitance in chapter Capacitance and Capacitors of Basic Electrical Engineering
Answer» The correct option is (d) Paper capacitor For explanation: The paper capacitor consists of TWO STRIPS of aluminium foil separated by sheets of waxed paper. This whole SETUP is rolled up into the form of a CYLINDER. Since the materials requires for its construction are easily available, it is the simplest KIND of capacitor.

Discussion

61.	If the thickness of the material increases, what happens to the dielectric strength?(a) Increases(b) Decreases(c) Remains the same(d) Becomes zeroThe question was asked during an online exam.My question is based upon Dielectric Strength topic in section Capacitance and Capacitors of Basic Electrical Engineering
Answer» Right option is (b) Decreases The best explanation: DIELECTRIC strength is the POTENTIAL GRADIENT required to cause a breakdown in the material. Potential gradient is the ratio of voltage and thickness. HENCE as thickness INCREASES, dielectric strength decreases.

Discussion

62.	A metal parallel plate capacitor has 100mm diameter and the distance between the plates is ‘a’ mm. The capacitor is placed in air. Force on each plate is 0.035N and the potential difference between the plates is 1kV. Find ‘a’.(a) 1m(b) 1cm(c) 10cm(d) 1mmThe question was asked in an interview for internship.This interesting question is from Force of Attraction Between Oppositely Charged Plates in portion Capacitance and Capacitors of Basic Electrical Engineering
Answer» RIGHT OPTION is (d) 1mm The explanation is: From the given data: A=pid^2/4=0.007854m^2 Potential GRADIENT = V/x = 1000/a F=epsilonA*(V/x)^2/2 Substituting the given values, we FIND a=1mm.

Discussion

63.	Energy stored in 2000mF capacitor charged to a potential difference of 10V is?(a) 100J(b) 200J(c) 300J(d) 400JI have been asked this question by my school principal while I was bunking the class.My question is based upon Energy Stored in a Charged Capacitor in portion Capacitance and Capacitors of Basic Electrical Engineering
Answer» The CORRECT option is (a) 100J The best I can explain: From the expression: WD = CV^2/2 = 100J.

Discussion

64.	A circuit has a resistance of 2 ohms connected in series with a capacitance of 6F. Calculate the discharging time constant.(a) 3(b) 1(c) 12(d) 8This question was posed to me in my homework.This intriguing question comes from Discharge of a Capacitor Through a Resistor topic in division Capacitance and Capacitors of Basic Electrical Engineering
Answer» RIGHT option is (c) 12 Explanation: The discharging time CONSTANT in a circuit consisting of a capacitor and resistor in SERIES is the product of the resistance and CAPACITANCE = 2*6 = 12.

Discussion

65.	____________ capacitors usually have a colour code to find its value.(a) Electrolyte capacitor(b) Variable capacitor(c) Polyester capacitor(d) Glass capacitorI had been asked this question by my school principal while I was bunking the class.The question is from Types of Capacitor and Capacitance in section Capacitance and Capacitors of Basic Electrical Engineering
Answer» The correct OPTION is (c) Polyester capacitor The best EXPLANATION: Polyester capacitors USUALLY come with a colour code because they are very small and their values cannot be PRINTED on its BODY.

Discussion

66.	Magnetic fields between the parallel plates of a capacitor are due to?(a) Displacement current(b) Conduction current(c) Both conduction and displacement current(d) Neither conduction nor displacement currentI had been asked this question during an interview.My doubt stems from Displacement Current in a Dielectric in division Capacitance and Capacitors of Basic Electrical Engineering
Answer» The correct option is (a) DISPLACEMENT current The EXPLANATION: Displacement current is the current which arises due to variations in the field. Change in the field results in the FORMATION of magnetic FIELDS. Hence displacement currents LEAD to magnetic field between the plates of a capacitor.

Discussion

67.	The current in conductors connecting the voltage source to the plates of a capacitor is ______(a) Conduction current(b) Leakage current(c) Charging current(d) ZeroThis question was posed to me in semester exam.I need to ask this question from Leakage and Conduction Currents in Capacitors topic in section Capacitance and Capacitors of Basic Electrical Engineering
Answer» Right option is (c) Charging current To EXPLAIN: The current in CONDUCTORS CONNECTING the voltage source to the PLATES of a capacitor is the charging current and not the conduction or LEAKAGE current.

Discussion

68.	When the area of cross section of the plate increases, what happens to the force between the plates?(a) Increases(b) Decreases(c) Remains the same(d) Becomes zeroI got this question in exam.I need to ask this question from Force of Attraction Between Oppositely Charged Plates topic in section Capacitance and Capacitors of Basic Electrical Engineering
Answer» RIGHT choice is (a) Increases For explanation: The force of attraction between the TWO plates of the capacitor is directly PROPORTIONAL to the AREA of cross section of the plates, hence an area of cross section increases, the force of attraction also increases.

Discussion

69.	When do we get maximum energy from a set of capacitors?(a) When they are connected in parallel(b) When they are connected in series(c) Both in series and parallel(d) Insufficient information providedThe question was asked in an online quiz.I would like to ask this question from Energy Stored in a Charged Capacitor in chapter Capacitance and Capacitors of Basic Electrical Engineering
Answer» The correct choice is (a) When they are connected in PARALLEL Explanation: We get maximum energy when capacitors are connected in parallel because the equivalent capacitance is larger than the LARGEST INDIVIDUAL capacitance when connected in parallel. The relation between capacitance and energy is: Energy=CV^2/2, hence as the capacitance INCREASES, the energy stored in it also increases.

Discussion

70.	Calculate di(0)/dt if the switch is closed at t=0.(a) -9.9A/s(b) -10A/s(c) 0A/s(d) -0.1A/sThis question was posed to me in examination.Asked question is from Transients in CR Networks in division Capacitance and Capacitors of Basic Electrical Engineering
Answer» The CORRECT choice is (d) -0.1A/s To explain: Applying KVL to the given CIRCUIT, we GET: i=i0e^-t/RC = (100/10)e^-t/100 i=10 e^-t/100 di/dt = -(10/100) e^-t/100 di(0)/dt=-0.1A/s.

Discussion

71.	The flow of electrons in dielectric is due to _________(a) Conduction(b) Potential difference(c) Breakdown(d) ResistanceI have been asked this question in final exam.I'm obligated to ask this question of Leakage and Conduction Currents in Capacitors topic in chapter Capacitance and Capacitors of Basic Electrical Engineering
Answer» The correct option is (C) Breakdown The EXPLANATION is: There is, under normal circumstance, no flow of electrons in a dielectric since a dielectric is basically an insulator. HENCE, there is a flow of electrons in a dielectric only at breakdown VOLTAGE.

Discussion

72.	What is the unit for displacement current?(a) No unit(b) Ampere(c) Coulomb(d) Ampere/coulombThe question was asked by my college professor while I was bunking the class.Enquiry is from Displacement Current in a Dielectric topic in section Capacitance and Capacitors of Basic Electrical Engineering
Answer» The correct OPTION is (b) AMPERE The explanation is: Displacement CURRENT is a type of current and hence it has the same unit as that of current that is ampere.

Discussion

73.	Which medium has the highest dielectric strength?(a) Water(b) Mica(c) Air(d) GlassThe question was posed to me during an interview.Query is from Dielectric Strength topic in portion Capacitance and Capacitors of Basic Electrical Engineering
Answer» RIGHT answer is (c) Air For explanation I WOULD say: The better material is to prevent electrical conductivity, higher the dielectric strength. And the air is the BEST INSULATOR so it has high dielectric strength.

Discussion

74.	If the potential difference in a material is 4MV and the thickness of the material is 2m, calculate the dielectric strength.(a) 2MV/m(b) 4MV/m(c) 6MV/m(d) 8MV/mThis question was addressed to me in an online interview.This key question is from Dielectric Strength topic in portion Capacitance and Capacitors of Basic Electrical Engineering
Answer» Right choice is (a) 2MV/m Easy EXPLANATION: Dielectric strength is the potential GRADIENT required to CAUSE a BREAKDOWN in the material. Potential gradient is the RATIO of voltage and thickness. Dielectric strength= V/t= 4/2= 2MV/m.

Discussion

75.	In an RC series circuit, when the switch is closed and the circuit is complete, what is the response?(a) Response does not vary with time(b) Decays with time(c) Increases with time(d) First increases, then decreaseThis question was addressed to me at a job interview.This interesting question is from Transients in CR Networks topic in division Capacitance and Capacitors of Basic Electrical Engineering
Answer» Right answer is (b) Decays with TIME For explanation: In an RC SERIES CIRCUIT, the response decays with time because ACCORDING to the equation, there is an EXPONENTIAL decrease in the response.

Discussion

76.	An 8microF capacitor is connected in series with a 0.5 megaohm resistor. The DC voltage supply is 200V. Calculate the current in the capacitor 4s after the power is supplied.(a) 79 microA(b) 68 microA(c) 48 microA(d) 74 microAThis question was posed to me by my college director while I was bunking the class.My question comes from Discharge of a Capacitor Through a Resistor topic in section Capacitance and Capacitors of Basic Electrical Engineering
Answer» CORRECT choice is (d) 74 microA Easy explanation: In the given question, the time constant is EQUAL to the time taken= 4s. Hence the value of current will be 37% of its initial value = I=0.37*200 = 74 microA.

Discussion

77.	While charging, what happens to the current in the capacitive circuit?(a) Decreases linearly(b) Increases linearly(c) Decreases exponentially(d) Increases exponentiallyThis question was posed to me in quiz.The above asked question is from Growth and Decay topic in section Capacitance and Capacitors of Basic Electrical Engineering
Answer» RIGHT choice is (c) Decreases exponentially To explain I would say: The EQUATION for the VALUE of current in a charging capacitive circuit is: I=I0(e^-t/RC). From this equation, we can SEE that the current is exponentially decreasing.

Discussion

78.	The unit for dielectric strength is ____________(a) V/m^2(b) MV/m^2(c) MV/m(d) VmThe question was posed to me during a job interview.My question is from Dielectric Strength topic in division Capacitance and Capacitors of Basic Electrical Engineering
Answer» Right CHOICE is (c) MV/m For EXPLANATION I would SAY: DIELECTRIC strength is the potential gradient required to cause a BREAKDOWN in the material. Potential gradient is the ratio of voltage and length, its unit is MV/m.

Discussion

79.	An 8microF capacitor is connected in series with a 0.5 megaohm resistor. The DC voltage supply is 200V. Calculate the time constant.(a) 1s(b) 2s(c) 3s(d) 4sThe question was asked during an interview for a job.Query is from Discharge of a Capacitor Through a Resistor in chapter Capacitance and Capacitors of Basic Electrical Engineering
Answer» The correct option is (d) 4s For EXPLANATION: The time constant is the product of the resistance and capacitance in a series RC circuit. Therefore, time constant = 810^-64*10^6=4s.

Discussion

80.	When will be capacitors fully charged?(a) When voltage is zero(b) When the supply voltage is equal to the capacitor voltage(c) When voltage is infinity(d) When capacitor voltage is equal to half the supply voltageThis question was addressed to me by my college professor while I was bunking the class.This is a very interesting question from Charging and Discharging Currents in portion Capacitance and Capacitors of Basic Electrical Engineering
Answer» The correct choice is (B) When the supply voltage is EQUAL to the capacitor voltage The explanation is: When the capacitor voltage is equal to the source voltage, it means that all the CHARGES have moved from ONE PLATE of the capacitor to the other.

Discussion

81.	The current equation for the given circuit is?(a) i=10e^(-0.01)t A(b) i=10e^(0.01)t A(c) i=10e^(-0.001)t A(d) i=100e^(-0.01)t AThis question was posed to me in an interview.This intriguing question comes from Transients in CR Networks in chapter Capacitance and Capacitors of Basic Electrical Engineering
Answer» The correct answer is (a) i=10e^(-0.01)t A Explanation: The KVL equation is: 100+10i(0)+1/10*integral(i(0)dt)=0 On APPLYING LAPLACE TRANSFORM to this equation, we get: 100/s=I(s)/10s+10I(s) Solving the equation, we get: i=10e^(-0.01)t A.

Discussion

82.	While discharging, what happens to the voltage in the capacitive circuit?(a) Decreases linearly(b) Increases linearly(c) Decreases exponentially(d) Increases exponentiallyThe question was asked in an international level competition.My doubt stems from Growth and Decay topic in section Capacitance and Capacitors of Basic Electrical Engineering
Answer» RIGHT choice is (c) DECREASES exponentially The best EXPLANATION: The equation for the value of VOLTAGE in a DISCHARGING capacitive circuit is: V=V0(e^-t/RC). From this equation, we can see that the voltage is exponentially decreasing.

Discussion

83.	A 8 microF capacitor is connected in series with a 0.5 megaohm resistor. The DC voltage supply is 200V. Calculate the time taken for the potential difference across the capacitor to grow to 160V.(a) 6.93s(b) 7.77s(c) 2.33s(d) 3.22sThis question was addressed to me in unit test.I want to ask this question from Discharge of a Capacitor Through a Resistor in portion Capacitance and Capacitors of Basic Electrical Engineering
Answer» The CORRECT answer is (a) 6.93s Easy explanation: From the previous explanations, we know that the INITIAL current is 400MA and the time constant is 4s. SUBSTITUTING the values of capacitor voltage, initial voltage, initial current and time constant in the equation: V=V0(1-e^-t/RC) Substituting V=160V, V0=200V, RC=4s we get, t=6.93s.

Discussion

84.	A circuit has a resistance of 2 ohm connected in series with a capacitance of 6F. Calculate the charging time constant.(a) 3(b) 1(c) 12(d) 8I got this question in an international level competition.Origin of the question is Growth and Decay topic in section Capacitance and Capacitors of Basic Electrical Engineering
Answer» Right choice is (c) 12 Best EXPLANATION: The charging time constant in a circuit consisting of a CAPACITOR and RESISTOR in series is the PRODUCT of the resistance and capacitance = 2*6 = 12.

Discussion

85.	Work done in charging a capacitor is ____________(a) QV(b) ^1⁄2QV(c) 2QV(d) QV^2I had been asked this question in class test.The query is from Energy Stored in a Charged Capacitor topic in portion Capacitance and Capacitors of Basic Electrical Engineering
Answer» CORRECT ANSWER is (b) ^1⁄2QV The best explanation: We know that work DONE= Q^2/2C. Substituting C as Q/V, we GET work done = Q/2V.

Discussion

86.	A capacitor is charged to a voltage of 400V and has a resistance of 20ohm. Calculate the initial value of charging current.(a) 10A(b) 0A(c) Infinity(d) 20AThis question was addressed to me in final exam.My query is from Charging and Discharging Currents topic in section Capacitance and Capacitors of Basic Electrical Engineering
Answer» The CORRECT answer is (d) 20A Easiest EXPLANATION: When the capacitor is charging the INITIAL value if the current is V/R=400/20 = 20A.

Discussion

87.	If the potential difference across the plates of a capacitor is 10V and a dielectric having thickness 2m is introduced between the plates, calculate the potential difference after introducing the dielectric. The electric field strength is 2V/m.(a) 4V(b) 6V(c) 8V(d) 10VThis question was posed to me in an international level competition.My doubt is from Composite Dielectric Capacitor in portion Capacitance and Capacitors of Basic Electrical Engineering
Answer» Correct CHOICE is (B) 6V To elaborate: When a dielectric is introduced between the plates of a capacitor, its potential DIFFERENCE decreases. New potential difference= potential difference without dielectric-potential difference of dielectric = 10-2*2 = 6V.

Discussion

88.	Calculate the relative permittivity of the second dielectric if the relative permittivity of the first is 4. The electric field strength of the first dielectric is 8V/m and that of the second is 2V/m.(a) 32(b) 4(c) 16(d) 8This question was addressed to me in unit test.This is a very interesting question from Composite Dielectric Capacitor topic in portion Capacitance and Capacitors of Basic Electrical Engineering
Answer» Right CHOICE is (c) 16 Easiest explanation: The relation between the two electric fields and the relative PERMITTIVITIES is: E1/E1=e2/e1. SUBSTITUTING the given values, we get e2=16.

Discussion

89.	What happens to the capacitance when a dielectric is introduced between its plates?(a) Increases(b) Decreases(c) Remains the same(d) Becomes zeroThis question was posed to me in homework.This interesting question is from Composite Dielectric Capacitor topic in chapter Capacitance and Capacitors of Basic Electrical Engineering
Answer» CORRECT answer is (a) Increases To EXPLAIN: The capacitance of a capacitance increases when a dielectric is introduced between its plates because the capacitance is RELATED to the dielectric constant K by the equation: C=k∈0A/d.

Discussion

90.	Potential drop in a dielectric is equal to _______(a) Electric field strengththickness(b) Electric field strengtharea of a cross section(c) Electric field strength(d) ZeroThe question was posed to me in an internship interview.I'd like to ask this question from Composite Dielectric Capacitor topic in section Capacitance and Capacitors of Basic Electrical Engineering
Answer» Correct choice is (a) ELECTRIC field strengththickness The BEST explanation: When a DIELECTRIC is introduced between the two plates of a parallel plate capacitor, the potential DIFFERENCE decreases by the VALUE of the product of electric field strengththickness which is the potential difference of the dielectric.

Discussion

91.	Find the capacitance of a multi plate capacitor whose relative permittivity=5, n=3, A=4m^2 and d=2m.(a) 1.7710^-10 F(b) 1.7710^10 F(c) 1.7710^-11 F(d) 1.7710^11 FThis question was posed to me in an online quiz.I would like to ask this question from Capacitance of a Multi Plate Capacitor topic in chapter Capacitance and Capacitors of Basic Electrical Engineering
Answer» The correct ANSWER is (a) 1.7710^-10 F Explanation: The formula for capacitance of a MULTI PLATE capacitor: C=Relative PERMITTIVITYABSOLUTE permittivity(n-1)A/d. C = 58.8510^-12(3-1)4/2=1.77*10^-10.

Discussion

92.	Strength of the electric field is ___________(a) Directly proportional to the force applied(b) Inversely proportional to the force applied(c) Directly proportional to the square of the force applied(d) Inversely proportional to the square of the force appliedThis question was addressed to me by my school teacher while I was bunking the class.My question comes from Electric Field Strength and Electric Flux Density topic in portion Capacitance and Capacitors of Basic Electrical Engineering
Answer» Right choice is (a) DIRECTLY proportional to the force APPLIED To EXPLAIN I WOULD SAY: Electric field intensity is the force per unit charge, hence it is directly proportional to the force applied.

Discussion

93.	Find the capacitance of a capacitor whose area of cross section of the plates is 4m^2 and distance of separation between the plates is 2m. The capacitor is placed in vacuum.(a) 1.7710^-11F(b) 1.3410^-11F(c) 2.3310^-11F(d) 5.6510^-11FThis question was posed to me in my homework.My question is based upon Relative Permittivity in chapter Capacitance and Capacitors of Basic Electrical Engineering
Answer» The correct answer is (a) 1.7710^-11F To ELABORATE: The expression for finding the VALUE of capacitance is: C=epsilonA/d. The MEDIUM is free SPACE hence, epsilon = 8.8510^-12. Therefore, C=8.8510^-124/2 = 1.7710^-12F = 1.77*10^-11F.

Discussion

94.	For which medium capacitance is high?(a) Air(b) Mica(c) Water(d) MetalThe question was asked by my college director while I was bunking the class.The origin of the question is Capacitance and the Capacitor in section Capacitance and Capacitors of Basic Electrical Engineering
Answer» The correct answer is (d) Metal Best explanation: Metals are ASSUMED to have a high VALUE of DIELECTRIC constant so they have high capacitance.

Discussion

95.	Calculate the voltage across the 6F capacitor.(a) 120V(b) 60V(c) 40V(d) 220VThe question was asked in unit test.I would like to ask this question from Distribution of Voltage Across Capacitors in Series topic in portion Capacitance and Capacitors of Basic Electrical Engineering
Answer» CORRECT option is (c) 40V To EXPLAIN: Capacitors are in series. 1/C=1/2+1/4+1/6, therefore, C=(12/11)F. Q = CV = 220(12/11) = 240C. V ACROSS 6F capacitor = Q/C = 240/6 = 40V.

Discussion

96.	Calculate the total charge of the system.(a) 200C(b) 100C(c) 300C(d) 400CThis question was addressed to me in final exam.My doubt is from Capacitors in Parallel in portion Capacitance and Capacitors of Basic Electrical Engineering
Answer» Correct ANSWER is (c) 300C The best explanation: The EQUIVALENT CAPACITANCE when capacitors are connected in parallel is the sum of all the capacitors=1+2=3F. Q = CV = 3*100 = 300V.

Discussion

97.	What happens to the potential drop between the two plates of a capacitor when a dielectric is introduced between the plates?(a) Increases(b) Decreases(c) Remains the same(d) Becomes zeroI got this question by my school teacher while I was bunking the class.Query is from Composite Dielectric Capacitor in section Capacitance and Capacitors of Basic Electrical Engineering
Answer» RIGHT option is (B) Decreases The BEST I can EXPLAIN: When a dielectric is introduced between the two plates of a parallel plate capacitor, the potential difference decreases because the potential difference of the dielectric is subtracted from it.

Discussion

98.	What happens to the capacitance of a multi plate capacitor when the area of cross section of the plate decreases?(a) Increases(b) Decreases(c) Remains constant(d) Becomes zeroThe question was posed to me during an online exam.I need to ask this question from Capacitance of a Multi Plate Capacitor in division Capacitance and Capacitors of Basic Electrical Engineering
Answer» Correct answer is (b) Decreases For explanation I WOULD say: When the area of CROSS SECTION decreases, the capacitance also decreases since it is related by the formula C=Actual permittivity(n-1)A/d. Here, we can SEE that the capacitance is directly PROPORTIONAL to the area of cross section.

Discussion

99.	Which is the correct expression for capacitance of a multi plate capacitor?(a) C=absolute permittivityA/d(b) C=Actual permittivity(n-1)A/d(c) C=Actual permittivity(n)A/d(d) Actual permittivity(n+1)*A/dI had been asked this question during an internship interview.I'm obligated to ask this question of Capacitance of a Multi Plate Capacitor in division Capacitance and Capacitors of Basic Electrical Engineering
Answer» CORRECT OPTION is (b) C=Actual permittivity(n-1)A/d Best explanation: The correct expression is: C=Actual permittivity(n-1)A/d. Where, n=number of plates, A=area of CROSS SECTION of the plates, d=distance of SEPARATION between the plates.

Discussion

100.	In uniform fields, all points have ________ field strength.(a) Zero(b) Same(c) Infinity(d) DifferentI got this question by my college director while I was bunking the class.My question is taken from Electric Fields in portion Capacitance and Capacitors of Basic Electrical Engineering
Answer» Correct choice is (b) Same The best I can EXPLAIN: A uniform field is one as the WORD suggests in which the field is spread over an area and at EVERY point in the field STRENGTH of the field is the same.

Discussion

Explore topic-wise InterviewSolutions in .

Which capacitors relatively costly?(a) Electrolyte capacitor(b) Mica capacitor(c) Air capacitor(d) Glass capacitorI have been asked this question in an online quiz.My question is taken from Types of Capacitor and Capacitance in division Capacitance and Capacitors of Basic Electrical Engineering

Calculate di(0)/dt if the switch is closed at t=0.(a) -9.9A/s(b) -10A/s(c) 0A/s(d) -0.1A/sThis question was posed to me in examination.Asked question is from Transients in CR Networks in division Capacitance and Capacitors of Basic Electrical Engineering

What is the unit for displacement current?(a) No unit(b) Ampere(c) Coulomb(d) Ampere/coulombThe question was asked by my college professor while I was bunking the class.Enquiry is from Displacement Current in a Dielectric topic in section Capacitance and Capacitors of Basic Electrical Engineering

Which medium has the highest dielectric strength?(a) Water(b) Mica(c) Air(d) GlassThe question was posed to me during an interview.Query is from Dielectric Strength topic in portion Capacitance and Capacitors of Basic Electrical Engineering

The unit for dielectric strength is ____________(a) V/m^2(b) MV/m^2(c) MV/m(d) VmThe question was posed to me during a job interview.My question is from Dielectric Strength topic in division Capacitance and Capacitors of Basic Electrical Engineering

Work done in charging a capacitor is ____________(a) QV(b) ^1⁄2QV(c) 2QV(d) QV^2I had been asked this question in class test.The query is from Energy Stored in a Charged Capacitor topic in portion Capacitance and Capacitors of Basic Electrical Engineering

For which medium capacitance is high?(a) Air(b) Mica(c) Water(d) MetalThe question was asked by my college director while I was bunking the class.The origin of the question is Capacitance and the Capacitor in section Capacitance and Capacitors of Basic Electrical Engineering

Calculate the voltage across the 6F capacitor.(a) 120V(b) 60V(c) 40V(d) 220VThe question was asked in unit test.I would like to ask this question from Distribution of Voltage Across Capacitors in Series topic in portion Capacitance and Capacitors of Basic Electrical Engineering

Calculate the total charge of the system.(a) 200C(b) 100C(c) 300C(d) 400CThis question was addressed to me in final exam.My doubt is from Capacitors in Parallel in portion Capacitance and Capacitors of Basic Electrical Engineering

In uniform fields, all points have ________ field strength.(a) Zero(b) Same(c) Infinity(d) DifferentI got this question by my college director while I was bunking the class.My question is taken from Electric Fields in portion Capacitance and Capacitors of Basic Electrical Engineering