Capacitors Questions and Answers

The charge on capacitors C C and C3 as shown in the figure ar respectively C 2 F C 4 F C 2 F 100 V 50 C 25 C 25 C 250 C 125 C 125 C 400 C 200 C 200 C

15 A capacitor of capacitance C is charged by a battery of emfe If polarity of battery is reversed then find the heat dissipated in the circuit E 1 C 2 20 3 30 4 40 16 In the circuit shown the galvanometer shows zero

Grouping of Capac charge A combination of capacitors is set up as shown in the figure The magnitude of the electric field due to a point having a charge equal to the sum of the charges on the 4F and 9uF capacitors at a point distance 30 m from JEE Main 2016 it would equal 11 2 F 3uF 20 9uF HI

The ratio between the energy stored in 5 F capacitor 43 fn s xs fp to the 4 F capacitor in the given figure is mtkZ dk vuc dev 1 1 2 3 1 25 422 www 4 F 2952 10V 5 F www 492 2 1 4 3 6 oneting 7 1 1 2 3 1 25

14 In the circuit the batteries have emf E E 1V E 2 5 V and the resistance R 102 R 20 2 capacitance C 10 F The charge on the left plate of the capacitor Cis 1 2 C Tus Tus Jus R ww C www R 2 4 C

When switch is shifted from 1 to 2 current through R remains same in direction but becomes 5 times The initial charge on capacitor was Q Final charge on capacitor is Q Find consider only the charge and currents in steady state R wwwww R HAH HH OD 2R

The net capacitance between point A and B as shown in the figure is A is plate area A 4 A d K A d O BAA d A K 1 d A K 1 A 4 B

A parallel plate capacitor of capacitance Chas been charged upto potential V The plates of this capacitor are connected to another identical uncharged capacitor The common potential acquired by the system is 2 Ov 2V Zero

4 Zero 3 10 m s 21 A capacitor having capacitance 1 F with air is filled with two dielectrics as shown Now capacitance of the system is La 1 2 F 3 4 F K 2 2 4 3 F 5 F

The charge on capacitors C C and C3 as shown in the figur are respectively C3 2 F 100 V HH HH C 4 F C 2 F 50 C 25 C 25 C 250 C 125 C 125 C 400 C 200 C 200 C 200uc 100 uc 100 uc

If the capacitance of a spherical conductor is 4 F then radius of sphere will be 3 6 10 m O 4 x 10 m 3 6 104 m 9 x 10 m

Consider a mixture of n moles of helium gas and 2 n moles of oxygen gas molecules taken to be rigid as an ideal gas Its Cp Cy value will be 1 67 45 3 23 15 2 19 13 4 40 27 ay JEE Main 2020 E

39 A thin metal plate P is inserted half way between the plates of a parallel plate capacitor of capacitance C in such a way that it is parallel to the two plates The capacitance now becomes b C 2 ges a C c 4 d 2C

with each other What is the minimum effective capacitance a 1 2 F c 2uF a 41 Three plates of common surface area A are connected as shown The effective capacitance will be J c A d b 1 F d 3uF 3 A 2 d d d b 3 A d 1 d 2A d 42 A parallel plate capacitor of capacitance 1 pF has separation between the plates is d When of coparation becomes 2d and c N by 47 Choose the correct sta a Polar molecules dipole moment b CO molecule is c H O is a non po d The dipole field 1 48 Which of the follow about Gauss s law a Gauss s law is b The term q on includes the su the surface c Gauss s law is electrostatic fi symmetry d Gauss s law

9 A parallel plate capacitor has an electric field of 105 V m between the plates If the charge on the capacitor plate is 1 C the force on each capacitor plate is 1 0 5 N 3 0 005 N 2 0 05 N 4 5 N

Combination of two identical capacitors a resistor R and a dc voltage source of voltage 6 V is used in an experiment on a CR circuit It is found that for a parallel combination of the capacitor the time in which the voltage of the fully charged combination reduces to half its original voltage is 10 second For series combination the time needed for reducing the voltage of the fully charged series combination by half is AIEEE 2011 1 2 5 second 3 10 second 2 20 second 4 5 second

Potential difference V in volts 25 SIT 20 15 10 5 0 50 100 150 200 250 300 Time t in seconds The figure shows an experimental plot for discharging of a capacitor in an R C circuit The time constant of this circuit lies between AIEEE 2012 1 0 and 50 s 2 50 sec and 100 s 3 100 sec and 150 s 4 150 sec and 200 s

89 An ideal cell of emf 10 V is connected in circui shown in figure Each resistance is 2 2 The potential difference in V across the capacitor when it is fully charged is R R R Im ww R 10 V JEE Main 2020 dh R

32 For the given input voltage waveform V t the output voltage waveform Vo t across the capacitor is correctly depicted by JEE Main 2020 1 ko www NII 10 nF 3 5V 4 OV 3 V 1 2V 2 2V 5 us IV t 2 V 0 H 5 us 10 us 15 s t V t 5 us 10 s 15 s V t M 5 s 10 s 15 s V t 2 V t V t T 84 85 Aak 86 Medical Divisions

The capacitance of a parallel plate capacitor with air as medium is 6 F With the introduction of a dielectric medium the capacitance becomes 30 F The permittivity of the medium is 50 8 85 x 10 12 C N m2 1 5 00 C N m 2 0 44 x 10 13 c N m2 3 1 77 x 10 12 C N m 4 0 44 x 10 10 C N m2

Fig shows a capacitor made of two circular plates each of radius 12 cm and separated by 5 0 mm The capacitor is being charged by an external source not shown in the figure The charging current is constant and equal to 0 15 A a 6 12 cm cm co Calculate the capacitance and the rate of change of potential difference between the plates Obtain the displacement current across the plates 12 cm

The capacitor of capacitance C can be charged with the help of a resistance R by a voltage source V by closing switch S while keeping switch S open The capacitor can be connected in series with an inductor L by closing switch S and opening S R S ONO S L Initially the capacitor was uncharged Now switch S is closed and S is kept open if time constant of this circuit is T then after time interval T Charge on the capacitor is CV 2 after time interval 27 charge on the capacitor is CV 1 e 2

1 State the principle of a capacitor Briefly explain why the capacitance of a parallel plate capacitor increases on introducing a dielectric medium betwe the plates

A dielectric slab of area A passes between the capacitor plates of area 2A with a constant speed v The variation of current i through the circuit as function of time t can be qualitatively represented as 3 A h t B D

charge exist at the centre of the square The Plates of a charged capacitor are connected by a voltmeter If the plates o the capacitor are moved further apart What will be the effect on the reading o the voltmeter

Four identical capacitors are connected in series with a 10 V battery as shown The point N is earthed The potentials of points A and B are ALE 1 10 V 0 V 3 5 V 5V F 10V CCC B C 2 7 5 V 2 5 V 4 7 5 V 2 5 V

11 The connections shown in figure 31 W9a are established with the switch S open How much charge will flow through the switch if it is closed 24 V F 1 F 2 F 4 a S 41 2 2 F 1 F 13 24 V To 1 F 2 F 4 HH Q2 Q2 b S Vo Q2 2 F 1 F HF Q Q

A parallel plate capacitor is charged by a battery When battery is removed and a dielectric material is inserted between the plates of the capacitor Which of the following does not change a Electric field between the plates b Potential difference across the plates c Charge on the plates d Energy stored in the capacitor

49 A capacitor of capacity 2 F is charged to a potential difference of 12 V It is then connected across an inductor of inductance 6 H What is the current in A in the circuit at a time when the potential difference across the capacitor is 6 0 V

For the R C circuit as shown initially capacitor is charged to potential VO with polarity as shown Switch S is closed at t 0 At t t0 current through R is half of its initial val ue find to V R www S

5 A cell E of emf 6 V and P E internal resistance 2 is 6V 20 connected with another cell E of emf 4 V and internal resistance 8 22 as X E Y 7 V 892 shown in the figure The potential difference across points X and Y is

potentials at A VA VB C VA VC D VA Vc Consider the situation shown in the figure The capacitor A has a charge q on it whereas B is uncharged The charge appearing on the capacitor B a long time after the switch is closed is A zero C q B q 2 D 2q 74 1 B A tipos of an equilateral

A 101 Bug 2 A parallel plate capacitor is made of two square plates of side a separated by a distance d d a The lower triangular portion is filled with a dielectric of dielectric constant K as shown in the figure 1 Capacitance of this capacitor is 1 ke a 2 d ke a 3 d K 1 K In K 2 2 k a d In K ke a 4 K

Question Which of the following characteristics of electrons determines the current in a conductor M 1 Point Drift velocity alone Thermal velocity alone Both drift velocity and thermal velocity Neither drift nor thermal velocity 333

Question Two insulated charged spheres of radii R1 and R2 having charges Q1 and Q2 respectively are connected to each other There is 1 Point no change in the energy of the system an increase in the energy of the system always a decrease in the energy of the system a decrease in the energy of the system unless Q2R1 Q1 R2

An air filled capacitor of capacitance C is completely filled with a dielectric material of dielectric constant k and then capacitor is connected to an ideal battery of emf V in series with a resistor of resistance R After steady state is reached the dielectric material inside the capacitor is suddenly removed After this instant the total heat produced in the resister is CV k 1 Where a b a

ers with capacities C 2C 3C and 4C are charge to the voltage V 2V 3V and 4V correspondingly The circuit is closed The voltage on the condensers in equilibrium is 4C 4V T 3C 3V 1 2c 2V A AV V B AV VC AV VD AV 19 5 C IF 14 V

If the capacitance ratio C figure is Answer A B C D C Your Attempt C n then the potential difference V between points M and N in the given C S OM ON Correct answer If E 110 V and n 2 then V 10 V If E 285 V and n 3 then V 15 V If E 110 V and n 1 2 then V 10 V If F 380 V and n 3 then V 20 V Rate this ques

The two plates of a parallel plate capacitor of capacitance C carry total charge Qand If a resistance is connected across t capacitor the total heat dissipated in the resistance until the current through it becomes zero is 2 Then Nis

2 28 A capacitor has charge 50 C When the gap between the plates is filled with glass wool then 120 C charge flows through the battery to capacitor The dielectric constant of glass wool is

Two capacitors of capacitances C and 2C are connected in parallel and are charged to a potential difference of V If now battery is removed an a material of dielectric constant k is placed between plates of capacitance C the potential drop across this capacitor will be 3 V 2 K 3V K 2 3K V 2 2V K 3

Two ideal inductors each of inductance L are connected in series and a capacitor of capacitance C is connected in parallel to one of the inductors This combination is connected across a battery of electro motive force through a switch Initially the switch was open for a long time and the capacitor was uncharged How will the voltage on the capacitor vary with time t after the switch is closed HH m F

Q A In the circuit shown in the Figure ABCD is a rect angular and vertical frame of conducting wires having three capacitors EFGH is in horizontal plane having two capacitors The two rectangular frames are connected at P and Q only Find equivalent capacitance between A and Gif each capacitor has capacitance C H E A C Q C B C P F C 2 5

figure is Answer A B C C D C Your Attempt C C OM ON Correct answer If E 110 V and n 2 then V 10 V If E 285 V and n 3 then V 15 V If E 110 V and n 1 2 then V 10 V If E 380 V and n 3 then V 20 V Rate this que

In the circuit shown in figure the applied potential difference between points A and B is 100 V then potential difference across 6 F capacitor is A 4 F 10 F BH 50 V 40 V 6 F O 20 V

Three capacitors of capacitance 18 F 9 F and 3 F are connected once in series and next times in parallel The ratio of equivalent capacitance in two cases Cp Cs is 9 1 06 1 15 1 09 4

A tuned circuit consisting of an inductor and a parallel plate capacitor of capacitance C with plate separation d has a resonating frequency L What will be the resonating frequency if a particle P of mass m and charge q is inserted in the middle of the capacitor plates Neglect effects of gravity fringing of electric field and electrostatic images

An isolated charged capacitor when filled with a dielectric k 3 has charge Q voltage V and electric field E If the dielectric is replaced by another dielectric K 9 the new values of charge voltage and field is 3Q 3V 3E O Q 3V 3E Ook 3E 1 E

Three identical capacitors and two identical batteries of negligibl internal resistance are connected as shown in figure Neglect the resistance of the wires and all the three switches are initially open There is no charge on any capacitor initially LE V S and S are closed and after some time S is also closed What is work done by battery d closing of switch S a CV2 b cv CV c cv d 2CV

37 8 Sri Chaitanya IIT Academy 13 11 16 Sr Super60 JEE ADV 2011 P1 RPTA 11 Q P reaching the end d the insect jumps into air such that it lands at the far end e of the plate 1 During the jump the insect s horizontal velocity remains same am d A 4dm 0V21 2 C dm V211 2 1 2 e The force acting on the dielectric slab due to charge on capacitor is A ELV 2d B ELV d D 4 LV d C 2 ELV d The time taken by the insect to move from a to d on the dielectric slab is A 4dm 0 V2 2 B 2dm 0V211 2 D dm 2 V 2 C dm 0V211 2 9 The time for which the insect will be in air during the jump is B 2dm 0V 1 2 D dm 2 V 11 2