Capacitors Questions and Answers

plates 59 An air filled parallel plate condenser has a capacity of 2 pF The separation 81 doubled and the interspace between the plates is filled with wax If the capacity is increased to 6 pF the dielectric constant of wax is 1 2 3 4 2 3 4 6

In the given circuit the potential difference between A and B is 18 V and charge on 2 F capacitor is 24 C The value of C is a cv 244 181 6X18 2 F HH A 1 1 F az cv 6 F HH 108 0 HH 12V 2 2 F B 108 24 1 x 2

57 A parallel plate air capacitor has capacitance C Now half of the space is filled with a dielec material with dielectric constant K as shown in figure The new capacitance is C Then 1 C 11 K 2 3 C C1 K Air 2 C C 1 K 4 C C K

2 58 A parallel plate air capacitor has capacitance C Half of space between the plates is filled wit dielectric of dielectric constant K as shown in figure The new capacitance is C Then c k K 1 C C 3 C K 1 2C Air 2 C C 2K K 1 4 C C 1 K

The V versus x plot for six identical metal plates of cross sectional area A is as shown The equivalent capacitance between 2 and 5 is Adjacent plates are placed at a separation d 10V 5V OV 1 2 3 4 5 X

The equivalent capacitance between point A and B is OCIA 2 52 A B C 14 3 C 4 20

26 A flat air capacitor C consists of two large plates that are close to each other Initially one of the plates was not charged while the other had charge Q If entire space between the plates is filled with a slab of finite electrical resistance estimate total amount of energy lost in the slab a c Q 20 3Q 8C b d Q 8C 7Q 8C

In the given circuit with steady current the potential drop across the capacitor must be R www 2 V 2 TT T H 2V C HH 2R www 3 V 3 4 2V 3 COCO

Two spherical conductors A and A of radii r and r are placed concentrically in air The two are connected by a copper wire as shown in figure Then the equivalent capacitance of the system is 1 41 kr 4 5 2 4 r r A r 3 4t 4 4 capacitor must he

A capacitor of capacitance C is charged to a potential V and then isolated A capacitor C is then charged from Co discharged and charged again the process is repeated n times Due to this potential of the larger capacitor is decreased to V then value of C is 1 Co V V 3 Co V V 1 4 Co V V 1 charged 1 uF capacitor are connected in a single loop circuit with a constant 2 C V V 1

An uncharged capacitor of capacitance 100 F is connected to a battery of emf 20V at t 0 through a resistance 1092 then i the maximum rate at which energy is stored in the capacitor is 1 10J s 2 20 J s 3 40J s ii time at which the rate has this maximum value is 1 4 In 2 ms 2 2 In 2 ms 3 In 2 ms 4 5J s 4 3 In 2 ms

In the adjoining diagram two geometrically identical capacitors A and B are connected to a battery Air is filled between the plates of C and a dielectric is filled between the plates of C then We sa 2 9 9 92 C TEK B C 3 9 9 9 A 4 None of these

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

The plates of a parallel plate condenser are being moved away with a constant speed v If the plate separation at any instant of time is d then the rate of change of capacitance with time is proportional to 3 d 4 d 1 2

A 3 mega ohm resistor and an uncharged 1 uF capacitor are connected in a single loop circuit with a constant source of 4 volt At one second after the connection is made what are the rates at which i the charge on the capacitor is increasing 1 4 1 e u C s 2 4e 3 C s 4 1 e C s 3 C S

An uncharged capacitor of capacitance 4 F a battery of emf 12 volt and a resistor of 2 5 MQ are connected in ser The time after which Vc 3V is take n2 0 693 1 6 93 seconds 2 13 86 seconds 3 7 seconds 4 14 seconds ed as shown in the figure with the switch S open When the switch is closed the total amoun

Two capacitors C and C are identical except that C has air between the plates and C has a dielectric of dielectric constant F Let q and q are the charges stored when capacitors are fully charged Now the dielectric slab is removed and the corresponding charges are Oq K 1 91 K 92 K 1 K 92 09 2 K 1 92 2K WWW OqK 91 2 and Then

A parallel plate capacitor C with plates of unit area and separation d is filled with a liquid of dielectric constant K 2 The level of liquid is initially Suppose the liquid level dicreases at a constant speed V the time constant as a d 3 function of time t is Figure 1 68 R 5d 3Vt 2 d 15d 9Vt R 2d 3d V1 9V wla 3 6E R 5d 3Vt www 15d 9Vt R 2d 3d Vt 9V 1

3 4 x 100 joule A fully charged capacitor has a capacitance C It is discharged through a small coil of resistance wire embedded in a thermally insulated block of specific heat capacity s and mass m If the temperature of the block is raised by AT the potential difference V across the capacitance is AIEEE 2005 2mCAT mCAT 1 2 3 msAT C 4 2msAT C atiualu If the capacitance

A parallel plate capacitor is made by stacking n equally spaced plates connected alternatively If the capacitance between any two adjacent plates is C then the resultant capacitance is AIEEE 2005 n 1 C 2 n 1 CO 3 C 4 nC

4 1 18 3 10 C m 2 8 1 10 C m Find the charge on 2 F 1 18 C 2 25 C 10 V 1 F 3 3 18 10 C m 5 F 2 F 10 V AIIMS 201 3 15 C 4 17 C danger of higher capacity to the condenser of lower capacity

The energy required to charge a parallel plate condenser of plate separation d and plate area of cross section A su that the uniform electric field between the plates is E is JAIPMT 200 1 E E Ad 2 E Ad 3 EAd E Ad

Two capacitors C and C are charged to same potential V but with opposite polarity as shown in the figure The switch S and S are then closed HF C C 0 p d across two capacitors are same and is given by p d across two capacitors are same and is given by C C V C C C V C C 0 ratio of final energy to initial energy of the system is given by C C C C C C C ratio of final energy to initial energy of the system is given by S S

1 4 A parallel plate capacitor is charged to 100 volts If a 1 mm thick plate is inserted between the plates of the capacitor distance between the plates required to retain the value of capacitance is 1 6 mm value of dielectric constant of the inserted plate is RPMT 2010 1 5 2 1 25 3 4 4 2 5 ation of four capacitors and their values are given Charge and potential difference acorss 4

After charging a capacitor the battery is removed Now by placing a dielectric slab between the plates 4 the potential difference between the plates and the energy stored will decrease but the charge on plates will remain same 2 the charge on the plates will decrease and the potentaial difference between the plates will increase 3 the potential difference between the plates will increase and energy stored will decrease but the charge on the plates will remain same 4 the potential difference energy stored and the charge will remain unchanged

If the shown figure combination of four capacitors and their values are given Charge and potential difference acorss 4 F capacitor will be RPMT 2010 1 600 C 150 Volt 300 ale 20 F CL 4 F 12 F HH 2 300 C 75 Volt 4 F 3 3 800 C 200 Volt 4 580 C 145 Volt illa plate condenser of plate separation d and plate

1 800 V 8 400 V 3 16 A capacitor of 6uF is charged to such an extent that the potential difference between the plates becomes 50 V The work done in this process will be 1 7 5 10 2 J 2 7 5 10 J 3 3 10 J 4 3 10 J dius and having same charge coalesce to form a big drop Capacitance of big drom

PHYSICS Three capacitors of same capacitance are connected in parallel When they are connected to a cell of 2 volt total charge of 1 8 C is accumulated on them Now they are connected in series and then charged by the same cell The total charge stored in them will be 1 1 8 C 2 0 9 C 3 0 6 C The equivalent capacitance between A and B of the combination shown in the fir 40 2 C CENY

In the given figure the capacitance of each capacitor is C then the effective capacitance between A and B will be 1 C 2 2 C A B C C C C 3 2C C 4 6C

n resistances each of resistance R are joined with capacitors of capacity C each and a battery of emf E as shown in the figure In steady state condition ratio of charge stored in the first and last capacitor is 1 n R R 2 n 1 n 1 C 3 n 1 n 1 4 1 1

4 remains decreases increases 4 decreases remains unchanged A parallel plate condenser is connected to a battery of c m f 4 volt If a plate of dielectric constant 8 is inserted int then the potential difference on the condenser will be 1 1 2 V 2 2V 9 4V 4 32V vill b

4 Maximum when the sheet is just near the ve plate The value of a capacitor formed by a thin metallic foil is 2 uF The foil is folded with a layer of paper having a thick ness of 0 015 mm The dielectric constant of the paper is 2 5 and its breadth is 40 mm The length of the foil used is 4 33 9 m 3 13 4 mm 1 0 34 m 2 1 33 m allol plote air capacitor is charged by connecting its plates to a battery Without disconnecting the battery a dielectric

A sheet of aluminium is inserted in the air gap of a parallel plate capacitor without touching any of the two plates of the capacitor The capacitance of the capacitor is 1 Invariant for all positions of the sheet 2 Maximum when the sheet is midway between the 2 plates 3 Maximum when the sheet is just near the ve plate 4 Maximum when the sheet is just near the ve plate The foil is folded with a laver of paper having a thick

The potential of earth is zero because it is 1 unchanged 3 an object of infinite capacitance two plates of the charged capacitor are connected by a wire then 2 an object of zero capacitanc 4 having infinite charge

The plates of a capacitor of capacitance 10 uF charged to 60 C are joined together by a wire of resistance 100 0 then i the charge on the capacitor in the circuit at t 0 is 1 120 C 2 60 C 3 30 C ii the charge on the capacitor in the circuit at t 100 us is 1 120 C 2 60 C 3 22 C iii the charge on the capacitor in the circuit at t 1 0 ms is 2 60 C 1 0 003 LC 3 44 C 4 44 C 4 18 C 4 18 C

1 3 2 2 5 3 2 Three capacitors 3uF 10uF and 15 F are connected in series to a voltage source of 100 V The charge on 15 F is 1 22 C 3 2800 C 4 200 C 2 100 C llel plates capacitors of value C and 2C are connected in parallel and are charged to a potential difference V d hotween the plates of the capacitor

A parallel plate capacitor is first charged and then a dielectric slab is introduced between the plates The quantity tha remains unchanged is Charge Q 2 Potential V 3 Capacity C 4 Energy U

The plates of parallel plate capacitor are charged upto 100 V A 2 mm thick plate is inserted between the plates Th to maintain the same potential difference the distance between the plates is increases by 1 6 mm The dielectric c stant of the plate is 1 5 2 1 25 3 4 4 2 5

17 ALI Five capacitors are connected to each other as shown ahead What is the potential drop and charge across 4 F capacitor D B HHH PH 18 F 6uF 4uF 8uF 18uF 1 6 V 30 C 3 6 V 40 C 30V 2 10 V 30 C 4 10 V 40 C

11 Two metal plates have potential difference of 300 V and are 1 cm apart A charged particle of mass 1 96 10 15 kg is held in equilibrium between the plates of the capacitor then the electric field will be 1 30 V m 3 3 V m 2 30000 V m 4 300 V m

Ques 3 A circuit consists of a resistance R ohm s and a condenser of C farads connected to a constant e m f If is the voltage of the condenser at time t after closing the circuit Show that the voltage at time t is E 1 eck

The equivalent capacitance of three capacitors of capacitance C C and C connected in parallel is 12 units and the product C C C 48 When the capacitors C and C are connected in parallel the equivalent capacitance is 6 units Then the capacitance are 2 4 6 2 1 5 6 10 Vi 3 1 5 2 5 8 4 2 3 7 lied between A and B a charge of 0 75 mC is stored in the system of ca

A capacitor of capacity C 1 uF can withstand maximum voltage V 6 kV and other capacitor C 3 uF can with stand maximum voltage V 4 kV If these are connected in series then the combined system can withstand a maxi 2 mum voltage at 1 4 kV 2 6 kV 3 8 kV 4 10 kV Conducting sphere of radius R is covered by concentric sphere of radius R Capacity of this combination is propor

Two capacitors of capacitances 3uF and 6uF are charged to a potential of 12V each They are now connected to each other with the positive plate of each joined to the negative plate of the other The potential difference across each will be 1 6V 2 4V 3 3V 4 Zero The aquiplant capacitance between the points A and B is

Two capacitors of capacity C and C are charged upto a potential V and V then condition for not flowing the charg between on connected them in parallel 1 C C 2 C V C V 2 3 V V 2 C C 4 V V

The equivalent capacitance of the circuit shown between points A and B HH 1 F 2 1 F 5 2 HF 1 F 1 F 2 F HH HF B 00 O 7 4 F

6 The equivalent capacitance in the circuit shown in figure will be 10 A 4uF 4 F B 4 F 3 6 F 4 F 4uF HH 4 8 F

Two capacitors are joined as shown in figure Potentials at points A and B are V and V respectively The potential of point D is 1 V V 2 A V HIC C V C V C C D 3 Hlc C V C V C C B 4 C V C V C C

The work done against electric forces in increasing the potential difference of a condenser from 20V to 40V is W The work done in increasing its potential difference from 40V to 50V will be 1 4W 2 3 W 4 3 2W 4 W 2

n identical condenser are joined in parallel and are charged to potential V Now they are separated and joined in ser Then the total energy and potential difference of the combination will be 1 Energy and potential difference remain same 2 Energy remains same and potential difference is nV 3 Energy increases n times and potentials differences is nV 4 Energy increases n times and potential difference remains same