Electric Field and Potential Questions and Answers

A point charge Q is placed at distance d from centre of a hollow sphere with inner radius a and outer radius b A point charge q is also pla at centre of hollow sphere Then the interaction potential energy of sphere and point charge q placed at centre will be Options kq 1 2 3 kQq kQq 6 1 b 1 b a d 04 Q d

Consider a thick conducting shell of inner radius R outer radius R as shown in the figure Shell is neutral and a point charge Q is kept at point A i e centre of shell Point B and D lie at distance r and r respectively from centre Choose CORRECT option s A Potential at point D is B Potential at point B is kQ KQ R 1 D R kQ KQ KQ R r R B er R C Potential at D will change if point charge shifted to position C D Potential at B will change if point charge is shifted to position C

a 24 A potentiometer wire of length 100 cm has a resistance of 10 2 It is connected in series with resistance and a cell of emf 2V having negligible internal resistance A source of emf 10 mV is balanced against a length of 40 cm of the potentiometer wire The value of external resistanc UP CPMT 20 is a 76022 b 640 Q

Please list all the formulas of Electrost atics I m saying Electrostatics please give w hole list of formulas that is in Electrost atics all energy field potential and ea ch and every formulas With their prope r name Whose formula belongs to who m

Equipotential surface differing in potential by 1volt are drawn around a positive charge particle The distance of the nearest surface differing in potential by 1V from the surface at 5V is 10cm The distance of the other surface differing by 1V from the 5V surface is

Consider a grounded conductor with a spherical cavity in it A point charge Qis placed in it The electric potential at centre of cavity is volts Given K 9 x 10 Nm C a 1m b m Q 1x10 C vyfde wa ut fear allery feest vas of fagya faha de 9x10 Nm C a 1m b mQ 1x10 C OPTIONS MARK FOR REVIEW a s

A hollow conducting sphere of inner radius Rand outer radius 2R is given a charge Q as shown in figure then the RB Raw 2 i fa il cafe arger and 1241 Q 2 2R OPTIONS MARK FOR REVIEW CLEAR SELECTION 23 Potential at A and Bis different A ABORTH BACH

Two thin rings each having radius 3R are placed at distance 4R apart with their axis coinciding The charges on the rings are Q and Q The potential difference between the centres of two rings is K 1 47 0

Two neutral insulating small spheres are rubbed against each other and are then kept 4 m apart If they attract each other with a force of 3 6 N then i calculate the charge on each sphere and calculate the number of electrons transferred from one sphere to the other during rubbing

2 C charge is shifted from Pto Q If workdone by external force in this process is 160 x 10 jo then potential difference between points Pand Qi e Ve Vois 2 OPTIONS MARK FOR REVIEW CLEAR SELECTION OA i par e Vot B 160 volt 160 led 160 volt 160 for 160 x 1 17

A charge Q is placed at the origin and another charge 2Q is placed at the point a 0 0 The surface of zero potential is a sphere whose centre is at radius of having a respectively a A 3 0 0 B C 2a 3 a 2a 3 0 0 3 2a a 2 0 0 3 3 2a0 03

10 Two conducting spheres have radii R 0 5 m and R 1 m Each of them has 300 C charge on its surface If the spheres are joined by a conducting wire then the amount of charge transferred from one body to the other is 1 100 C 3 150 C 2 50 C 4 200 C

A small sphere having charge Q is fixed at one position and two identical point charges q having mass m are kept on a line passing through centre of sphere The point charges are connected by a rigid rod of length and mass m and this assembly is free to move along the line connecting them When the point K neglect effect of charge nearer to sphere is at a distance 3 from centre of sphere then gravity 1A Paper 2 Code D Acceleration of rod is Acceleration of rod is 25 KQq 432 ml Tonginn nt 25 KQq 216 ml 1 All India A q Tension at one of the ends of the rod is zero if Q ho onde of the rod is zord if ds 216 9 115 q 2

A thin dielectric rod of length I lies along the x axis with o ne end at origin and other at the point 1 0 It is uniformly charged with total charge Q If field and potential at point P 21 0 is E and V respectively then

2 The charge flowing through a resistance R varies at bt2 where a and b are with time t as Q at positive constants The total heat produced in R is INEET 2016 a R a a R 3b b a R 2b c a R b d 6b

A conductor has a cavity inside it Which of the following statements is true A The electric field inside the cavity is zero irrespective of whether there is a charge inside the cavity or not B The electric field inside the cavity is zero only if there is no charge on the conductor C The electric field inside the cavity is zero only if the cavity is spherical D Any two points inside the cavity are at the same potential if there is no charge inside the cavity

35 Assertion A Two protons placed at different distances between the plates of a parallel plate capacitor experience the same force Reason R The electric field between the plates of the capacitor is constant Both A and R are true and R is the correct explanation of A 1 point Both A and R are true but R is NOT the correct explanation of A A is true but R is false A is false and R is also false

20 cm In force on a centre of ERT Pg 46 5x10 7C d at points 0 15 cm moment of RT Pg 46 7 Cm pol is found 6 1 Consider charges q q and q placed at vertices of an equilateral triangle as shown in figure Calculate force on q charge due NCERT Pg 17 to other 1 2 l 3 q q 4 ol 39 4 1 29 TE Which among the given statements is 9 statement among the following is field then the correct INCERT Pg 46 1 Time required to fall through certain distance is more for an electron 2 The force experiences by proton will be more 3 Magnitude of acceleration experienced by proton is more KE gained by both charges in moving through same distance are equal Regarding electric lines of force the correct statement is are NCERT Pg 24 1 Field lines carry information about direction of electric field 2 Relative density of field lines 2021 09 08 23 18

7 Work done by external agent in assembling three identical charges from infinity to given locations is 1 3 91r rar 5 q 8 r 5 q 2 r Los 4 NCERT Pg 62 5 q 8 r 3q 8 10 When a conductor is placed electric field Then IN 1 At the surface of conducte field is normal to the su point 2 Inside the conductor e is zero 3 The electrostatic potem throughout the volume has the same value on 4 All of above are correc

3 A system of two charges A 2 5 10 7C and q 2 5 10 7C are located at points 15 cm and B 0 0 15 cm respectively The electric dipole moment of A 0 0 system is NCERT Pg 46 1 2 5 10 7 Cm 7 5 10 8 Cm 2 5 x 10 7 Cm 4 Zero 1 3 q 2TE 29 El

The region between two concentric conducting spherical shells of radii r and r b ra is filled with a poor conducting material The inner sphere is maintained at a potential V and outer sphere is at lower potential V as a result of which current is there in radially outward direction The variation of electric field intensity as a function of distance r from centre of sphere is given by En En A E E C En EE E Tb B D EE E En E Eb

7 Three concentric metallic shells A B and C of radi a b and c a b c have surface charge density o o and a respectively If A and C are kept at same potential then C is equal to 1 b a 3 b a 2 4 b a 2 b a 2

A non conducting disc of radius Ris given charge in such a way that charge density on the disc is given by a a following question Potential at the center of disc is O R 46 20 R 380 where is constant and ris radial distance Based on this answer the

26 In the circuit shown in figure E 2E 20 V R R 10 k and C 1 F Find the current through R R and C when R E S LLI E B R a S has been kept connected to A for a long time b The switch is suddenly shifted to B ww

The magnitude of electric field experienced by a charge at a certain distance from a source charge is equal to 64 N C What will be the magnitude of the electric field at four times that distance and with a source charge half as strong A 64 N C B 2 N C C 128 N C D 1 N C

In an LR circuit the a c source has a voltage 220 V If the potential difference across the inductance is 176 V then the potential difference across the resistance will be OA 132 V B 145 V OC 44 V OD 396 V

A non conducting rod AB of length 3 R has uniformly distributed charge of linear charge density nonconductor ring has uniformly distributed charge Q Point A is the centre of ring and line AB is the axis of ring perpendicular to plane of ring Choose the correct statement s A R 2 B

In Column l configuration of charges are given Column Il gives the location of null point E 0 and potential at null point Match the entries of two columns Column l q 0 0 q Q1 Q2 Q3 Q4 0 0 q 0 0 0 0 9 49 d 0 4q d 0 9q d 0 d 0 9q Column II A1 2 0 A2 d 0 A3 0 A4 0 9 4 od A5 V

EXAMPLE 153 Eleven equal wires each of resistance r form the edges of an incomplete cube Find the total resistance from one end of the vacant edge of the cube to the other the other Solution Let A and B be the vacant edges of the cube Let an emf applied across AB send a current 2x in the circuit Since the paths AD and AE are symme trical the current 2x at A is divided into two equal parts x and x At other points the current is divided as shown in Fig 3 164 so that again the currents combine at B to give current 2x Let R be the total resistance of the cube between A and B ni gniwoli tnsmus sil H 2 x y Chto sonatai 2910s sales to sounterest sell hidrosa yu S y nghs an E A noitonj x y si lo vilsmmx di D yi 1 ni mwore as od wuditiay ng X x y 150119 F HA G x y adus ont to Crisq falisisq

34 A uniform wire of resistance 92 is joined end to end to form a circle Then the resistance of the circular wire between any two diametrically points is Kerala CEE 2014 3 d 2 2 a 60 e 15 b 3Q c 2 02 4 Jont resistance of two resistors connecte

Two charges 2 C and 2 C are placed at 10 cm 0 0 and 20 cm 0 0 respectively in the presence of a uniform external electric field of 2 x 104 V m directed towards positive x axis The total electrostatic energy of the configuration will be 356 J 360 J O 360 mJ

a spherical cavity with radius R inside this sphere with a negative point charge Q located in its center Find a Charge on the inner and outer surface of the conducting sphere b Electric field and electric potential in the cavity inside and outside of the sphere c What is the potential difference voltage between inner and outer surfaces of the sphere 2R

Two point charges A q m and B 2q m are placed at rest at separation of in uniform electric field E as shown If separation between charges remains constant and 2 3 then value of Eis ng Find n m E Answer B

A solid sphere of radius R having uniform volume charge density p is shown in figure A spherical cavity of radius difference between centre of cavity and centre of sphere then V PR2 12 B V PR2 60 D Electric field inside the cavity is Electric field inside the cavity is PR OR 20 is hollowed out from sphere If Vis potential

In Column I configuration of charges are given Column Il gives the location of null point E 0 and potential at null point Match the entries of two columns Column 01 02 03 0 0 04 0 0 0 0 0 0 d 0 40 d 0 9q d 0 d 0 99 Column 11 A1 A2 00 A3 A4 bin Bin O AS V

Two point charges A q m and B 2q m2 are placed at rest at separation of in uniform electric field Eo as shown If separation m between charges remains constant and m Find n E B Answer 0 01 02 03 04 05 06 07 01 02 04 05 3 then value of Eo is CO 07 08 9

Two point charges q and q2 are placed a distance r apart in vacuum An infinite dielectric slab of thickness and dielectric constant k 4 is placed between them Which of the following statements is are true regarding magnitudes of various forces 59 92 A Net electrostatic force on q2 is given by F B Force on q due to q is given by F 9192 4 eor 9192 97801 C Force of interaction between dielectric slab and q2 is given by F3 59192 36

A quarter disc of radius R placed as shown has uniform surface charge density o A point P 0 0 R is located in space Let E and be the z component of the field and potential at point P then 0 E U E V V G 8 G 8 1 GR 480 1 2 GR 2 1 Beo 2 1

The figure shows some of the equipotential surfaces The magnitud and direction of the electric field is given by y cm 10 V 20 V 30 V 40 V 30 10 20 30 40 x cm 200 V m 60 with x axis O200 V m 120 with x axis 100 V m 30 with x axis O 100 V m 120 with x axis

7 The potential difference that must be applied to stop the fastest photoelectrons emitted by a nickel surface having work function 5 01 eV when ultraviolet light of 200 nm falls on it must be a 2 4 V b 1 2 V c 2 4 V d 1 2 V 2010

A small bob of charge Q and mass 5 kg is suspended with the help of an ideal string and an ideal spring of K 5 x 10 N m so that the spring is in its natural length An insulated point charge of Q is fixed on the ground as shown with distance between two charges as 50 cm When the string is cut the maximum elongation of the spring is 10 cm If NX 25 3 ms 2 T 8 teeeeeeee C where N is an integer then find N g 10 Q 50 cm

4 a c b 15 5 A charged water drop of radius 1 mm and charge of 104nC is just suspended in air in vertical plane in presence of vertical uniform electric field The intensity of electric field is approximately 1 400 N C 2 200 N C 3 40 V mm 4 20 V mm 4 a c b referat f1 mm 104 nc fa fer un faga ffi faciant a faga a un staan enn 1 400 N C 2 200 N C 3 40 V mm 4 20 V mm

18 Neutral metal sphere of radius R is connected to Yea earth through a switch S which is initially open Two charges 3Q and 2Q are kept at 9R and 3R distances from the centre of the sphere as shown When switch is closed the charge flown from the sphere to the earth is 1 Q 3 Q S 3R 9R 4 2Q 2 Q 2Q 3Q

A solid conducting sphere having a charge Q is surrounded by an uncharged concentric conducting hollow speherical shell Let the potential difference between the surface of the solid sphere and that of the outer surface of the hollow shell be V If the shell is now given a charge of 3Q the new potential difference between the same two surface is Question Type Single Correct Type 1 2 3 V 2V 4V

17 Plot a graph showing the variation of coulomb force F versus 1 r where r is the distance between the two charges of each pair of charges 1 C 2 C and 2 C 3 C Interpret the graphs obtained

ge 2m an electron has intrinsic angular momentum I called spin and a permanent magnetic dipole moment M L associated with the spin where e is the positive electron charge mis me electron mass and g is a number called g factor An electron with its spin aligned along its initial velocity in the x direction enters a region of uniform magnetic field in the z direction ue to magnetic force the torque on the spin is MX B and perpendicular to M also perpendicular to I Since torque is perpendicular to I therefore it ensures that the spin turns with itial angular velocity pwhich is given by the following equation px ue to charge on the e magnetic force also acts on the electron hat is the value of p 11

Two conducting spherical shell of radii R 2R given charges Q and 2Q respectively Inner shell is provided with a switch which can ground the inner shell as shown Switch is initially open and energy stored in the system is U After the switch is closed energy stored in the system is found to be U Finc U U 2Q Q R 2R S TTTTTTT

A disk of radius a 4 having a uniformly distributed charge 6C is placed in the x y plane with its centre at a 2 0 0 A rod of length a carrying a uniformly distributed charge 8C is placed on the x axis from x a 4 to x 5a 4 Two point charges 7C and 3C are placed at a 4 a 4 0 and 3a 4 3a 4 0 respectively Consider a cubical surface formed by six surfaces x a 2 y a 2 z a 2 The electric flux through this cubical surface is NC 80 The value of Nis

A thin non conducting semi circular ring of radius R has a linear charge density cose where Xo is constant then X Total charge on ring is R Total charge on ring is 2 oR Electric field at center of ring is Electric field at center of ring is 20 880R 20 480R

Question No 5 The figure shows a circular ring of radius R 0 5 m and mass 0 5 kg Part ABC and ADC carries uniform charge and TC When uniform electric field of 1 N C is applied and ring is slightly rotated about its axis and released Find the angular frequency in rad sec of small oscillation D B L