Electric Field and Potential Questions and Answers

A and B are two large parallel conducting plates of area 2 m on each side A is given a charge of 2 0 C and B is given a charge of 1 0 C If separation between A and B is 8 85 mm then potential difference VA VB will be 10 x k volt find value of k A B Answer 0 08 09 01 02 03 04 05 06 07

A dipole of dipole moment P is placed at a distance x from the center of a non conducting ring of radius R The ring has a total charge Q uniformly distributed on its circumference as shown in figure For x 0 magnitude of force of interaction between QP A 1 dipole and ring is F where A B TEO RC and B are integer in simplest forms Then find the value of product ABC F 4 A P a ya faya Avu Hudc ddu H 4 G 92 20 21 Ted Byur day ukf uz a Yuga 59 faara x 0 y a ulzu fcu da X J P B TEO R quic 1 aa ABC QYake Ki AA Ma Af

In a medium the force of attraction between two point electric charges distance d apart is F What distance apart should these be kept in the same medium so that the force between them becomes i 3 F ii F 3

A uniformly charged non conducting hollow sphere of radius 1m and mass 2kg having angular speed wo 9 rad s is gently placed on non conducting rough horizontal surface with coefficient of friction at t 0 Charge on the sphere is Qo and uniform electric field E is present in the region parallel to horizontal surface given QoE 10 N g 10m s Then match the column Column I 1 If 0 6 then acm till 1 s If 0 4 then acm till 1 s E L Column II A along ve x axi B along ve x axi C zero D non zero

An electron e in a TV picture tube is accelerated from rest through a potential difference of 5000 Volts a As the electron moves is it accelerating from high electric potential to low electric potential or from low electric potential to high electric potential b What is the change in the potential energy of the electron c What is the final speed of the electron

You measure an electric field of 1 38x10 N C at a distance of 0 153 m from a point charge There is no other source of electric field in the region other than this point charge Part A What is the electric flux through the surface of a sphere that has this charge at its center and that has radius 0 153 m VALS Submit et Amer 7 N m C

1 72 W 2 40 W 3 8 W 4 32 W Variation in electric potential is maximum if one goes 1 along the line of force 2 perpendicular to the line of force 3 in any direction 7 4 no variation in any direction One end of a spring of force constant k is fixed to a 8 1 72 W farga fara 1 tenen geen 2 marra 3 ffm 4 ff vt fem ke fra eft fein any form 2 40 W 3 8 W fram af 4 32 W m m

14 A charge Q is placed at each of the opposite corners of a square A charge q is placed at each of the other two corners If the net electrical force on Q is zero then Q q equals a 1 b 1 c d 2 2 2

If initially flux through hemisphere is zero Now q and q2 placed according to figure Due to which charge flux through hemisphere wil change 1 Only 91 9 2 Only 92 92 1

43 A thin spherical conducting shell of radius R has a charge q Another charge Q is placed at the centre of the shell The electrostatic potential at point A at a distance R 2 from the centre of the shell is Q 2q 1 A E OR 3 2Q q 4 s R Q q 2 ATER 4 2Q 9 4 E R 45

Figure shows three circular arcs each of radius R and total charge as indicated The net electric potential at the centre of curvature is Q 1 2 3 2Q Q 2 R Q 4 R 2Q TEOR Q 45 R 30 3Q

An infinite line charge of uniform electric charge density lies along the axis of an electrically conducting infinite cylindrical shell of radius R At time t 0 the space inside the cylinder is filled with a material of permittivity and electrical conductivity The electrical conductive in the material follows Ohms law Which one of the following graphs best subsequent variation of the magnitude of current density j t at any point in the material A B j t 0 0 j t

An electric dipole is rotated in uniform electric field fron stable equilibrium position The graph represents Variation of its potential energy is given by C f 9 2 AU P 3

An electric dipole is placed along x axis 40 a farga faya feargun x 3 sfeer you fare at the origin as shown in the figure Electric field at the point P is parallel to the y axis If x coordinate of P is 2 m what is its y coordinate 94 1 Im 3 3 m P x y 2 2 m 4 4 m fed fare fag af Pax 2 mt at y fa X affer 1 Im 3 3 m 94 P x y 2 2 m 4 4 m

A me sphere is charged so that surface charge density be o The mechanical stress pressure by the surface is equal to experienced 1 20 2 O 2 20 0 3 20

3 An electric dipole of dipole moment 10 9 C is directed towards negative Y axis and is kept at origin If in this region electric field is along positive Y axis and is 104 N C then the force and torque on the dipole is 1 10 N zero 2 104N zero 3 Zero zero 4 10 13 N zero

24 C charge is uniformly distributed on a ring of radius 4 cm The electric potential on the axis of ring at 3 cm from the centre of ring is 1 225 volt 2 450 volt 3 675 volt 4 900 volt 29

At what distance from the surface of sphere of charge charge is uniformly distributed of radius R the electrostatic potential is half of the potential at the centre 1 3 2R 3 4R 3 R 2 3 4 R 4

23 The electric potential in a region is given by V 2 2x 5y 4z The magnitude of electric field in the region is gr2 vim 3 7 V m 2 6 V m 4 14 V m

est AI 8 the centre of face AFGH of a cube Let flux passing through surface BCDE is then the flux through the face ABCH will be G 12 6 F E D B1 2 H C 2460

6 Identify the wrong statement in the following Coulomb s law correctly the electric force that a Binds the electrons of an atom to its nucleus b Binds the protons and neutrons in the nucleus of an atom c Binds atoms together to form molecules d Binds atoms and molecules to form solids

Q 3 Three positive charges of equal value q are placed at the vertices of an equilateral triangle The resulting lines of force should be sketched as in see fig a O a O b O d b d

2 rods are aligned on the yaxis the first from y a to y b snd the second from y c to y d the charge Der unit length on both rods is the same find electric field surounding the system as a function of x and y

27 A particle having charge q and mass m is released from rest on the axis of a fixed ring of total charge Q and radius R from a distance 3R Its kinetic energy when it reaches the centre of ring is 1 3 R O Qq 4 E R Qq 2 R 3 R 2 4 m q Qq 8 R Qq 16 R

Point charge m has mass 4M and charge 2Q Initially m is to the left of m and separated by a distance D in deep space where Earth s gravity is negligi The particles are shot away from each other along a straight line with speeds 2V and V respectively The magnitude of the acceleration of m related to its initial speed is related to m in an unknown way is equal to that of m None of these answers is correct O O O O is smaller than m O is larger than m is zero

Assertion When two protons are brought closer to each other against their electrostatic repulsion th their combined mass becomes slightly more than their total mass Reason If we bring two similar charges closer to each other from infinity then work is needed to be against electrostatic repulsion Mechanical work against electrostatic repulsion gets stored in the sy as electric energy We know that E mc2 hence due to an increase in energy of the system equiva mass of the system increases Use the following key to choose appropriate answer Options OIf both assertion and reason are correct and reason is a correct explanation of the assertion OIf both assertion and reason are correct but reason is not the correct explanation of assertion

A charge water drop of radius 0 1 m is under equilibrium in some electric field The charge on the drop equivalent to electronic charge The intensity of electric field is g 10 m s 2 26 2 NC 1 3 262 NC 1 4 1610 NC 1

Three charges q q and 2q are placed at three vertices of an equilateral triangle of side 1 The magnitude of net force on the charge Q placed at the centroid of the triangle as shown in the figure will be 4 3Qq 1 A o 3Qq 29 2 0 Qq 416

Two infinite linear charges are placed parallel at 0 1 m apart If each has charge density of 5 C m then the force per unit length of one of linear charges in N m is 1 2 5 2 3 25 3 4 5 4 7 5

Consider the charges q q and 2q placed at the vertices of an equilateral triangle as shown in the figure The net electrostatic force on the system of charges will be 29 9 1 3 39 2 4 E 2 9 5q 4 4 Zero

nce between centres of two spheres A and B each of radius R is r as shown in figure 1 450 Sphere B has a spherical cavity of radius R 2 such that distance of centre of cavity is r R 2 from the centre of sphere A and R 2 from the centre of sphere B Di electric constant of material of each sphere is K 1 and material of each sphere has a uniform charge density p per unit volume Calculate interaction energy of the two spheres B 26m A Figure 1 450

21 4 Both A charge q is placed at the centre of the line joining two exactly equal positive charges Q The system of three charges will be in equilibrium if q is equal to 1 Q 3 01 Q 4 2 2 4 Q 14 176

Consider the following arrangement in which three point charges are placed along x axis as shown 4 c 2 C 1 c 0 X 0 x 30cm 110 8N X x 45cm The net force acting on 2uc charge is 6N 3 04N 4 1 2N

uestion Type MCQ Question No 22 A particle of charge 16 x 10 8C moving with velocity 10 ms 1 along the positive x axis enters a region where a magnetic field of nduction B is along the positive y axis and an electric field of magnitude 10 V m is along the negative z axis If the magnetic field is switched off and the same electric field is maintained the path of the particle is O Circle O Parabola Straight line Mark s 4 00 Negative Markis 1 00 O ellipse Physics Se Pran Choose a 22 conge 19 25 28

Electric Charges and Fields 43 A uncharged solid conducting sphere of radius r is placed at a distance d from a particle having charge q Find electric field at point P just inside the surface due to induced charge appearing on the sphere 1 q 1 4d along PC 1 q 2 4 d r along CP 1 q 3 4 d r along PC 46 47 48

58 An electron is rotating around an infinite positive linear charge in a circle of radius 0 1 m if the linear charge density is 1 C m then the velocity of electron in m s will be mula 1 0 562 107 2 5 62 107 3 562 107 X 4 0 0562 107 sir to box 18 q1 2TTE m

Q1 1 A Find the electric potential V x y z at point in cartesian coordinates due to a dipole placed on xy plane as shown in the figure The coordinates of the negative and positive charges are a 0 0 and a b 0 respectively B Find the electric field vector E x y z C what is the work to be done to move q from its original position to infinite 9 9 V x y z y

If 2 parallel plates have a potential difference of 50 0 V between them What is the separation between these plates required to produce an electric field of magnitude 651 N C in units of meters

20 Four point charges q 6 C q 8 C ac 6 C and q 8 C are located at the corners of a square ABCD of side 3 2 cm The net electrostatic force on a 1 c placed at the centre of the square will be 1 80 N 2 60 N 3 120 N 4 160 N

15 Figure shows the field lines of a positive charge If a small negative charge is released at point Q then the sign of potential energy difference of negative charge between the points Q and P will be 1 Positive 2 Negative 3 Zero 4 Either positive or negative

6 Calc permittivity 4 the distance between in two charges is 40cm 7 The force between two charges when separated by a distance of 100cm is 30m what will be the force between them if distance becomes 50cm of 50cm in air is 4

5 An early model for an atom considered it to have a positively charged point nucleus of charge Ze surrounded by a uniform density of negative charge up to a radius R The atom as a whole is neutral as shown in the figure The R magnitude of electric field at a distance r 2 from centre will be 1 3 Ze 8re R 3Ze 8 R ze Pag 2 4 7Ze 8 R 3Ze 4TE R

25 Sphere is charged uniformly If one moves from A to B along diameter AB then electric field AX B 1 First increases then decreases 2 First decreases then increases 3 Remains same 4 Zero

Magnitude of electric field due to an electric dipole at a distance r from it at axial position is given as E The magnitude of electric field due to the dipole at a distance 2r from it on equatorial line is 8 E 16

Question No 4 Single Correct A short diple of dipole moment p 21 31 6 k Cm is placed at origin the electric potential at position 1 j k mis 11 3 10 V 33 10 V 11 3 10 v A A zero

e 1 63 Four charges q q q and q are placed in order on the four consecutive corners of a square of side a The work done in interchanging the positions of any two neighbouring charges of the opposite sign is 9 A 4 2 4 K 4 4 2 2 B D 9 4 4 2 2 q 4 4 2

fagyalaya AY DAHEIGH OPTIONS MARK FOR REVIEW CLEAR SELECTION A The dimensions of dipole moment is LTA faya nu a face LTA The SI unit of dipole moment is C m m Dipole moment is vector quantity and directed from negative charge to positive charge Dingle moment in

Consider the following two statements A Electrostatic field lines do not form closed loops B In the direction of electrostatic field the potential increases The incorrect statement s among the above is are Aya fur dagu A Rurday Rait de qu Affa adi and B Ferdaya f r faha a d 34RIFA YA OPTIONS MARK FOR REVIEW CLEAR SELECTION OA OB OC Only A ad A Only B B Both A and B AB

In a region a uniform electric field is given by E 21 6j 8k NC The electric flux through a sphere of radius 1 m centered at the origin is yur dial fagya Y E 1 6 8 Gially for my OPTIONS MARK FOR REVIEW CLEAR SELECTION OA 8 N m C B Zero 24 O C 10 N m C OD 16 N m c

In a region a uniform electric field is given by E 21 61 8k NC The electric flux through a sphere of radius 1 m centered at the origin is Bia IUHHay Ga E 2 6j 8k NC RIQ i d U H ng edim sumd in d i degg Ueda OPTIONS MARK FOR REVIEW CLEAR SELECTION OA 8 N m C OB Zero 24 C 10 N m C D 16 N m C