Capacitors Questions and Answers

Two identical capacitors are joined in parallel charged to a potential V separated and then connected in series i e the positive plate of one is connected to the negative plate of the other Then 1 Charges are destroyed when free plates connected together 2 Charges on the free plates are destroyed 3 The energy stored in the system increases 4 The potential difference between the free plates is OV

147 Figure shows three capacitors connected to a 6 supply What is the charge on the 2 F capacitor a 1 C b 2 C c 3 C d 4 C 1 F H 2 F 3 F TH HH 6 V

3 51 A metal ball of radius a is surrounded by a thin concentric metal shell of radius b The space between these electrodes is filled up with a poorly conducting homogeneous medium of resistivity p Find the resistance of the inter electrode gap Analyses the obtained solution at b 7 C r C

13 in the situation shown in figure the switch is at position I for long time and its has shifted from position I to position 2 at t The current in the 3 12 resistor at t 31m 2s is found to be x x A Find the value of x 36V ww 8 1092 402 12 V 12 39 www 250 m

39 In the circuit shown in figure heat developed across 4 22 and 3 2 resistances are in the ratio of a 2 4 3 b 8 4 12 c 4 8 27 d 8 4 27 292 W 492 www 352 M

B 101R 100 respectively A battery of emf is A spherical shell capacitor is made of inner and outer radius R and connected between the two shells The approximate energy stored by the capacitor will be 1 100T RE 2 400 E RE 3 200 E RE 4 800 R A hollow sphere of radius 2R is charged to V volt and another sphere of radius R is charged to V 2 volts Now the smaller sphere is placed inside the bigger sphere without changing the net charge on each sphere The magnitude of potential difference between the two spheres would be

Att 0 the switch S is closed with the capacitor uncharged If C 50 F 50 V and R 5 0 kn how much energy is stored by the capacitor when I 2 0 mA Select one O O O a 28 m b 36 mJ c 32 m3 d 40 mJ e 20 mJ C S R 6

Three identical large metal plates of ar ea A are small at distances d and 2d fr om each other Top metal plate is unch arged while other metal plates have ch arges Q and Q Top and bottom metal plates are connected by switch S throu gh a resistor of unknown resistance W hat energy in mJ is dissipated in the r esistor when switch is closed give e A d 6milliF Q 60milliC

9 Consider the situation shown in figure The switch S is open for a long time and then clo HH HH S F E Match the Column I and Column II and mark the correct option codes a b Column I Charge flows through cell when S is closed Work done by battery when S is closed c Change in energy stored when S is closed d Heat developed when S is closed Column II p CE2 2 q CE 2 r CE214 s CE218

1 A capacitor of 2uF is charged as shown in the figure When the switch S is turned to position 2 the percentage of its stored energy dissipated is NEET 2016 2 RS 2 F 75 c 80 8 F d 0

5 Two large metal plates are originally oriented horizontally and separated by a distance of 3 d A conducting wire joins them and initially plates are uncharged A third identical plate with charge Q is put parallel to them at a distance of d from upper plate Then a charge on lower plate is T 3d Q 3 2Q 3 2d b charge on upper plate is c potential difference between upper and middle plate is 2Qd 3 A Qd d potential difference between upper and lower plate is 38 A

nitial charges on both the capacitors are CV Find change in potential energy of both if a battery is connected as shown Also find the work done by battery C 9in CV HIE 3C 9in CV Initially t 0 V 1 C HH 3C

3 The distance between plates of a parallel plate capacitor is 5d The positively charged plate is at x 0 and negatively charged plates is at x 5d Two slabs one of conductor and the other of a dielectric both of same thickness d are inserted between the plates as shown in figure Potential V versus distance x graph will be A C Od 2d 3d 4d 5d Od 2d 3d 4d 5d 91 IU C d 2d 3d 4d 5d CONDUCTOR B q D Od 2d 3d 4d 5d VA Od 2d 3d 4d 5d

Area of one side of each plate is A and separation between consecutive plates is d Emf of the battery connected is V The charge on plate 2 is A 1 1 A V d A V d 41 2 2 3 4 2A V d 2A V

In the circuit shown in figure the current gain 100 for a npn transistor what should be the base resistor Rg so that VCE 5V VBE 0 RB www IB 2 105 Q 1 2 10 Q VBE 3 2 1050 1KQ RL Question Type Single Correct Type Ic VCE I 10 V

A charged particle having charge q and mass m accelerated by a potential difference Venters inside a parallel plate capacitor parallel to length of plates at midpoint of its separation between plates at t 0 Potential difference across capacitor varies with time t as V adt where a is constant and dis separation between ma plates Angle of deviation as it comes out of plates is Value of 2qV will bati

A capacitor of 10 uF is charged to a potential 50 V with a battery The battery is now disconnected and an additional charge 200 C is given to the positive plate of capacitor New potential difference across the capacitor will be 1 50 V 2 60 V 4 100 V 3 80 V

V dc source It remains connected to the source Using an insulated handle the distance between the plates is doubled and a dielectric slab of thickness 5 mm and dielectric constant 10 is introduced between the plates Explain with reason how the i capacitance ii electric field between the plates iii energy density of the 211

V de source It remains connected to the source Using an insulated handle the distance between the plates is doubled and a dielectric slab of thickness 5 mm and dielectric constant 10 is introduced between the plates Explain with reason how the i capacitance ii electric field between the plates iii energy density of the capac

Three very large metal plates are given charges as shown in the figure If cross sectional area of each plate is same then final charge distribution on plate C is 2Q 4Q 10Q A B A B C outer surface C inner surface 5Q on inner surface and 5Q on outer surface 6Q on inner surface and 4Q on outer surface 7Q on inner surface and 9Q on outer surface 20 on innor surface and 20 on outer

A parallel plate capacitor is charged by certain amount of charge Q The force of interaction between the plates is F If region between the plates is filled by a dielectric material the force of interaction between the plates is F The correct statement is A F F C F F B F F D none of these

Two identical parallel plate capacitor are placed in series and connected to a constant voltage source of Vo volt If one of the capacitors is completely immersed in a liquid with dielectric constant K the potential difference between the plates of the other capacitor will change to Vo 2 K 1 K 3 K 1 1 Vo 4 K K 1 2K K Vo Vo

A capacitor of capacitance C is charged to V D potential The positive plate of this capacitor is now connected to the negative terminal of Vo potential difference battery and vice versa Calculate the heat developed in the connecting wires 1 2CV2 2 CV 2

A dielectric slab of dielectric constant 4 is inserted between the plates of one of the two identical capacitors as shown in figure to fill the space completely The potential difference across the other capacitor is 1 4 V HHH 10 V 1 2 6 V

A parallel plate capacitor consists of two square plates each of side 4 cm separated by a distance of 4 43 mm The displacement current if potential difference between the plates changes at the rate of 5 x 10 V s is 160 A 120 A 80 A 86 A

capacitance C one another as ential at O 10 Find the potential difference V V between the points a and b shown in each part of figure a 6V 24 V 4 F 2 F 1 F b

Two equal capacitors of capacitance 10 F are connected as shown in figure After one is charged to a potential of 50V and the other is given a charge of 1mC A capacitor of capacitance 20 F is charged to 0 1 Joule and connected across AB with positive terminal at A Find the final charge on each capacitor HE 10 F C Imc T T10 F B

67 Few capacitors are connected to a battery of 12V What will be charge on each capacitor in C 5 F 2 F 2 F HH HHH 12V 5 F

As shown in the figure At the steady state find the charges on 1uF and 3 F capacitors respectively 252 ww 1uF HH 352 ww 2 F 18 V 452 ww 2 F HH 352 www 3 F A 6 27 C 27 C 3 C 8 C a

Two metal spheres of radii a and b are connected by a thin wire Their separation is very large compared to their dimensions The capacitance of this system is 1 4 ab 3 4TE a b 2 2 a b 4 None of these

An arrangement of a parallel plate capacitor a spring and a battery is shown in the figure One plate of the shown parallel plate capacitor PQ is fixed while the other is attached to the wall by a spring and can move parallel to the plate P The two plate are joined to a battery through a key S which is initally open When the key is closed the plate seperation d decreases by n When the key is closed for a very short time intervel the separation decreases by x The ratio x d is given by H P Hill mmmm me K Q A n 1 n C n B n n 1

c 15 kW d 9 kW 0 A condenser of capacitance 12 F was initially charged to 20V Now potential difference is made 40V The increase in potential energy is a 7 2 x 10 J c 3 x 104 J m b 4 10 3 J d 5 x 106 J

and C 2 F are charged to a potential difference of 100V but with opposite polarity as shown Switches SiandS are now closed What is the potential difference between points a and b ao S C 0 X S C

180 O 500 V m Two parallel plates are of potential 20 V and 40 V If the separation between them is 4 cm The electric field between them is O 1000 V m 2000 V m Mark for Review O 1500 V m 02 5 hr m

Three capacitors of 2 F 3 F and 5 F are independently charged with batteries of emf s 5V 20V and 10V respectively After disconnecting from the voltage sources These capacitors are connected as shown in figure with their positive polarity plates are connected to S and negative polarity is earthed Now a battery of 20 V and an uncharged capacitor of 4 F capacitance are connected to the junction S as sh with a switch S When switch is closed find a the potential of the junction A b final charges on all four capacitors 2 F HH A 3 F 5 F 20V S 4 F

When the switch S is closed Find a the amount of charge flown through the battery b the heat generated in the circuit c the energy supplied by the battery d the amount of charge flown through the switch S

You set up the circuit shown in Figure 1 where C 3 20 x 106 F At time t 0 you close the switch and then measure the charge q on the capacitor as a function of the current i in the resistor Your results are given in the table below i mA 56 0 48 0 40 0 32 0 24 0 q uC 10 1 19 8 30 2 40 0 49 9 Figure i 0 Switch open 9 0 JL 1 of 1 un Switch closed T i q q

connected as shown in figure If the potential difference across the 7 F capacitor is 6V then which of the following statement s is are correct A B C 12 F HH 3 9 F 7 F 3 F The potential drop across the 12 F capacitor is 10V The charge in the 3 F capacitor is 42 C The potential drop across the 3 F capacitor is 10V

QTwo capacitors A and B with capacities 3 F 2 F respectively are charged to a potential difference of 100 V and 180 V respectively The plates of the capacitors are connected as shown in the figure With one wire from each capacitor free The upper plate of A is positive and that of B is negative An uncharged capacitor C with lead wires falls on the free ends to complete the circuit Final charge on capacitor having capacitance 3 F will be C 2 F H H

material of dielectric constant Its electric potential versus position graph is as shown Distance between the two plates is 4 mm The dielectric constant of medium Potential in volts 10 3

What is the charge stored on capacitor X if points a and b in the diagram to the right are kept to a potential difference of 36 0 Volts a 10 uF X 6 0 uF 12 F

ph Q en current and time during charging of a capacitor by a battery in series with a resistor is shown The graphs are drawn for two circuits R R C C and V V are the value of resistance capacitance and EMF of the cell in the two circuits If only two parameters out o resistance capacitance EMF are different in the two circuits What may be the corred option s a V V R R C C e V V R R C C Log 2 t b V V R R C C d V V R R C C

23 A capacitor of capacitance C 1 0 F charged upto a voltage V 110 Vis connected in parallel to the terminals of a circuit consisting of two uncharged capacitors connected in series and possessing the capacitance C 2 0 F and C3 3 0 F What charge will flow through the connecting wires potential difference of 20 V Find

Two capacitors of capacitances 3 F and 6 F are charged to a potential of 12 V 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 a 3 V b zero c 6 V d 4 V

32 A network of six identical capacitors each of value C is made as shown in the figure The equivalent capacitance between the points A and B is T 1 CIA f 2 3 4 3 320 B H J c 2 THI 4C 4 4 3 c12

228 Five identical plates each of area A are joined as shown in the figure The distance between the plates is d The plates are connected to a potential difference of V volt The charge on plates 1 and 4 will be 1 2 5 XX S 5x15x5 stoel 2 X

166 Electrostatic Potential and Capa 15 In the given circuit the electric potential of P will be 1 5 V 11V 1 F 2 F 3 F HHAH P 2 6 V 4 9 V

A capacitor is fully charged with the help of a battery and then capacitor is removed and connected to the same voltage battery but in opposite polarity Calculate time required to completely discharge the capacitor Time constant is 5s 1 3 465 sec 2 4 576 sec 3 5 687 sec 4 6 798 sec

X A conducting sphere S of radius 1 cm is connected to a parallel plate air capacitor C of plate area 9 102 m and plate separation 8 85 mm The capacitor is earthed with the help of switch S and inductor L 20 mH as shown in the figure The sphere is imparted a charge qo 36 C and switch is closed at t 0 The maximum current in the circuit after closing the switch is A 12 10 A C 20 A B 24 10 A D 10 A

Three capacitors C1 C2 C3 whose values are 10 F 5 F and 2 F respectively have breakdown voltages of 10 V 5 V and 2 V respectively for their interconnection shown below find the maximum safe voltage that can be applied across the combination in V AO C C3 OB