Capacitors Questions and Answers

Which of the following graph best represents the variation of impedance IZ of parallel LC circuit with co 1Z1 IZI 1 3 121 LC LC 00 4 N 0 121 LC IC 0 8

A dielectric slab of thickness d 2 and dielectric constant 2 is inserted in capacitor as shown in figure If capacitor is connected to 10 V emf battery then find potential difference between the two surface A and 8 of dielectric slab 1 2 3 Otroct Answer 4 Our Answer 3 atus incorrect 4 V 20 3 5V 10 3 V D

A parallel plate capacitor formed by square plates of side length separated by a distance d d is filled with a material whose dielectric constant varies linearly from K to 2K along x The capacitance of the capacitor with the dielectric medium will be

An air filled parallel plate capacitor has capacitance C When a dielectric medium of dielectric constant k is introduced to fill half of the space between the plates as shown the capacitance becomes 2C The value of k is

glish A parallel plate capacitor of capacitance C is connected to a battery and is charged to a potential difference V Another capacitor of capacitance 2C is connected to another battery and is charged to potential difference 2V The charging batteries are now disconnected and the capacitors are connected in parallel to each other in such a way that the positive terminal of one is connected to the negative terminal of the other The final energy of the configuration is Options 1 O zero 2 O 3 O 25CV 3CV 2 9CV

No 24 View In English 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 DH 3 Correct Answer 1 Your Answer 2 Zero q 2 q 29 B

32 Capacity of parallel plate capacitor with a medium of dielectric constant 8 is 12 F If the medium is removed then capacity of the capacitor would be O 96 F O 1 5 F O 0 67 F O 18 F 1

Options 1 O A 3d View In English v The expression for the equivalent capacitance of the system shown is A is the cross sectional area of one of the plates of side a 3 2 O d 4 30A 0A 6d none of the above 3d

mathon mathor If qf is the free charge on the capacitor plates and q is the bound charge on the dielectric slab of dielectric constant k placed between the capacitor plates then bound charge q can be expressed as mathor 1 f 1 mathongo mathongo mathongo mathongo mathon 2 ab af 1 qf mathongo mathongo mathonga mathongo mathon af 1 qf 4 qb q 1 1 mathongo mathongo mathongo mathongo 3 ab mathe

Six identical capacitors each of capacitance C are connected as shown The equivalent capacitance between points A and Bis A WIN 314 00 0 0 Read More 2C E B

1 ZArak 2 4 Arak 3 Arak 2AE 4 Zero 1000 small water drops each of capacitance C join together to form one large spherical drop The capacitance of bigger sphere is 1 C 2 10 C 3 100 C 4 1000 C For shown situation in steady state condition ratio of charge stored in the first and lost th 25 26 1 2Ark 2 4Arck 3 Arck 1000 unten C 1 C 2 10 C 3 100 C 4 1000 C gefeta feefa ford tranff WE

0 Find the potential difference across point a and b 10 fa fa fa for in fig Telegram ne questionpaper 3 5 6 The charges on two parallel conner plates 11 C C C 3 6 8 C 4 C C C

25 A big hollow metal sphere A is charged to 100 voli and another smaller hollow sphere B is charge to 50 volts If B is put inside A and joined with metallic wire then the direction of charge flow 1 is from A to B 2 is from B to A 3 no charge flows

A parallel plate capacitor formed by square plates of sid length separated by a distance d d is filled with a material whose dielectric constant varies linearly from K to 2K along x The capacitance of the capacitor with the dielectric medium will be X O EK1 d O EK1 2d O 3 K1 2d

parallel plate capacitor has capacitance 5 50 F a How much energy is stored in the capacitor if it is connected to a 15 00 V battery 10 b If the battery is disconnected and the distance between the charged plates doubled what is the energy stored A c The battery is subsequently reattached to the capacitor but the plate separation remains as in part b How much energy is stored 10

Two metal spheres of radii a and b are connected by a conducting wire Their separation is very large as compared to their dimensions The capacitance of this system is Only one correct answer A B C 4 E0 ab 2 a b 4 a b ab i

A circuit is connected as shown in the figure with the switch Sopen When the switch is closed the total amount of charge that flows across Sis A O Only one correct answer B 54 pC 3 F HH C 27 C 302 9V 6 F 60 www G

R R C C 3 2 points Consider the circuit shown in Figure le The battery has an EMF of 60 0 V and negligible internal resistance R2 2 002 C 3 00F and C2 6 00 F After the capacitors have reached their final charges the charge on C1 18 02C a What is the final chargo on C22 b What is the value of

Briefly explain the following instructions and indicate the operand no of bytes taken no of machine cycles with proper explanation like Fetch Read Write and no of T states in each machine cycle 4 a XTHL b CALL unconditional c RESTART d JUMP unconditional e RET

There are two identical square metallic plates kept on a rough horizontal floor at t 0 plates are given angular velocity and it is given that plate 1 is rotating about its centre A and plate 2 is rotating about one of its corner O If t and t are the time taken by both the plates to come to rest then is Both are independent cases t A 1 2 30 12711 O B 2 D 4

You are provided with a large number of identical capacitors each of capacitance 2uF and potential 5 volt How many capacitors should you use and how to get a net capacitance of 5uF and a potential of 20 volt

2 In the circuit shown figure C luF and C 2uF Capacitor C is charged to 100V and C to volts After charging they are con nected as shown When the switches S S and S all are closed C 100 V C 20 V No charge will flow through S A charge magnitude 80 C will flow through S Acharge magnitude 40 C will flow through S Acharge magnitude 60 uC will flow through S

A series LCR circuit is connected to an AC source of variable frequency When the frequency is increased continuously starl from very small value the power factor a kada ng AC for a fa e HA URA GI R FRAR LCR a di da vida quis A Goes on increasing continuously PROIR CECI ERI SIL B Goes on decreasing continuously Apar ucala JUTI C Remains constant faud 21 D Becomes maximum at a particular frequency food Prica angla BUH BI GIAL

A circuit contains uncharged capacitor resistor and a battery as shown The switch is closed at t 0 and the system is allowed to attain steady state Now the switch is opened Pick the CORRECT statement s f R www S A Heat generated in resistance till steady state is CV B If after a long time switch is opened and a dielectric is inserted between the complete volume within the capacitor then the new energy stored in capacitor is kCV 2 C If after a long time switch is opened and a dielectric is inserted between the complete volume within the capacitor then the new energy stored in capacitor is D Ratio of electric field just after and before dielectric is inserted is 1 CV 2k

Two metal spheres of capacitance C and C carry same charges They are put in contact and then separated the final charges Q and Q on them will satisfy 1 3 ala ala ala V II A Q els ls l

2 20 Four capacitors each of 1 F are joined as shown in figure The equivalent capacitance between the points A and B is A C C C HH C B

Electrostatic and Capacitance Example 2 78 Figure shows a combination of twelve capacitors each of capacitance C forming a cube Find the equivalent capacitance of the combination i between the diagonally opposite corners A and B of the cube ii and between the diagonally opposite corners A and D of a face of the cube A B C D

13 In a parallel plate capacitor the region between the plates is filled by a dielectric slab The capacitor is connected to a cell and the slab is taken out Some charge is drawn from the cell Some charge is returned to the cell c The potential difference across the capacitor is reduced d No work is done by an external agent in taking the slab out

An R C series circuit is charged in two ways In first case it is connected to the terminals of a cell of emf 2E In second case it is connected to the terminals of a cell of emf E After getting fully charged with E it is connected to cell of emf 2E and charged till saturation In second case as compared to first case P List I Saturation charge on capacitor Maximum energy stored in capacitor 2 R Energy supplied by cell s 3 S Heat generated in resistor 4 List II Increases if the cells are ideal Decreases if the cells are ideal Remains same if the cells are ideal Data is incomplete to predict formation

Chapter 21 Electric Current and Direct Current Circuits 1 Given C 2 5 F C 4 5 F C 3 3 F and C 1 5 F what is the equivalent capacitance of the four capacitors between A and B Find the current I through the battery Note that the battery has an internal sistance of 0 4 ohms 30 V 0 492 A 44 5 00 WW AF 7 00 5 0 92 3 00

1 If a source is connected to points a b the charge on all capacitors are equal If it is connected to points m n then also charge on all capacitors are equal m 2 F C 5 F n A C 3 5 F B C 2 F C If source of voltage 6 volts is connected between m b charge on C 5 C D If source of voltage 6 volts is connected between a n the charge on C 2 C

R R earthed concentric sphere of radius R R R The ratio is INGLE CHOICE QUESTIONS Capacity of an isolated sphere of radius R is increased n times when it is enclosed by a A n 1 B n n 1 C 2n n 1 D 2n 1 n 1

In the circuit shown in figure the equivalent capacitance between the points X and Y is 1 F HH A 2uF 4 F B 3uF X HH 2 F C 4 F Y 4 F D 5 F

Q33 A parallel plate capacitor of area A plate separation d and Capacitance C is filled with three different dielectric materials having dielectric constants K K K3 as shown If a single dielectric material is to be used to have the same capacitance C in this capacitor then its dielectric constant K is given by a c d 1 1 K 1 1 K 1 K K2 K K K K2 K K3 K K3 K K3 K K3 1 K3 1 2 K3 2K3 d A 2 K1 K3 Q A 2 K2 H

1 Identical metal plates are located in air at equal distance d from one another The area of each plate is equal to A Evaluate the capacitance of the system between P and Q if the plates are interconnected as shown in Fig 4 72 a C OP 2 OP 5 Po b d P Q B3E04 Ceq 2 dp 0 G Cs CP

The circuit is in steady state Now a zero resistance wire is joined between points A and B If the heat dissipated after joining the wire is nCV then find the value of n Round off to two decimal places A C www 2C

A paralleled plate capacitor has circular plate of diameter 5mm and separation between the plate is 2mm a Calculate the capacitance of the capacitor b Find the charge on each plate of the capacitor when battery of 16Vis connected c What is the electric field between the capacitor plates when a material is filled in the space between plates has dielectric constant of 6

1 On a capacitor of capacitance Co following steps are performed in the order as given in column I A Capacitor is charged by connecting it across a battery of EMF V B Dielectric of dielectric constant k and thickness d is inserted C Capacitor is disconnected from battery D Separation between plates is doubled Column I Steps performed ROMAYE A a d c B d a c b C b a c d D a b d c Column II Final value of Quantity Symbols have usual meaning P Q Q Q R C S V C V 2 kC V k 1 kCo k 1 V k 1 2k ATHE

A parallel plate capacitor is half filled with water in vertical direction Waters permitivity is 1 3 times higher than air What is the capacitance in UF if the plates are square with side 8m and 3mm apart eo 8 84 10 12C V m

5 A parallel plate capacitor consists of two circular plates each of radius 2 cm separated by distance question 0 1 m If voltage across the plate is varying at of 5 x 1013 V s then value of displacement current is 7 60 A 3 5 56 A 2 5 56 10 A 4 2 28 x 10 A

Two concentric shells of radii a and 2a are placed far away from a parallel plate capacitor of capacitance C Plates are given and 90 Switches S and S are charges 90 2 closed at t 0 After steady state is reached physical quantities are asked in List I and value of corresponding physical quantities are listed in List II C 4 2a cu cur a Ych Um az t T Hmka zu o 90 32 2 2 0 ga 1 zy gazu ura Mz yM 1 Hag af 43 y n am ym 11 Hac uf u ma sed C 4 I List l f 1 pof 31 4132 Charge on inner shell is 9 Value is 90 90 2 Qcapacitor is ka S Energy stored in spherical 2 nq 90 Rcapacitor is Codes 3 S C 91 1 ka f Energy stored in parallel plate n19 91 90 Value of nis 2 nq 90 Energy loss as a result of 2 n390 S switching is 20 Razzy Guf A 36C ka ka Gulf Value of n is A P2 Q3 R 4 S 1 B P 3 Q 2 R 4 S 1 chl in Value of n3 is n3q 20 P 3 01 R 4 S 2 n190 36C List II 1 3

34 In the given LC circuit charge q on capacitor is given by graph as shown in the figure questionpaper q Which of the following graphs best represents current in circuit 1 N time 3 time time time time

52 The capacitance of a parallel plate capacitor is Co If a dielectric of dielectric constant K and thickness C equal to one fourth the separation is placed between the plates then capacity becomes C Then ratio is FC K at 1 5K 4K 1 2 4K 3K 1 3 3K 2K 1 font such a 4 2K K 2

27 In an LCR circuit inductance is changed from L to L to keep the same resonance frequency C should 2 be changed to 1 20 plo 8 014 4 4C

a b I The two plates of a capacitor hold 2800 C and 2800 C of charge respectively when the potential differ ence is 930 V What is the capacitance I How much charge flows from a 12 0 V battery when it is connected to a 12 6 F capacitor

29 A finite ladder is constructed by connecting several sections of 2 F 4 F capacitor combinations as shown in figure 31 E18 It is terminated by a capacitor of capacitance C What value should be chosen for C such that the equivalent capacitance of the ladder between the points A and B becomes independent of the number of sections in between A 4 F HF 2 F HF 2 F 2 F 4 F FC

Two identical parallel plate capacitors A and B are connected in series through a battery of potential difference V see figure Area of each plate is a and initially plates of capacitors are separated by a distance d Now separation between plates of capacitor B starts increasing at constant rate u the rate by which work is done on the battery when separation between plates of capacitor B is 2d is p of p is B HH a vV 9d value

How many 1 F capacitors must be connected i parallel to store a charge of 1 C with a potential 110 V across the capacitors 1 990 3 9090 2 900 4 909

A parallel plate cap square parallel plates of area A and separated by a distance d The capacitor is connected to a battery with potential V and allowed to fully charge The battery is then disconnected A square metal conducting slab also with area A but d thickness is then fully inserted between 2 the plates so that it is always parallel to the plates How much work has been done on the metal slab by external agent while it is being inserted 1 1 A v 4 d Eo 2 1 A v 2 d

usto A 3 F capacitor is charged to a potential of 300 V and 2 F capacitor is charged to 200 V The capacitors are then connected in parallel with plates of opposite polarities joined together What amount of charge will flow when the plates are so connected 1 1300 C 2 800 C