Electric Field and Potential Questions and Answers

The potential at a point due to an electric dipole will be maximum and minimu when angles between axis of dipole and line joining the point to dipole are respectively 0 120 0 90 90 180 O 0 180

Two positive charges are kept at a 0 and a 0 A negative charge then let from a position 0 y y al The negative charge will perform O Oscillatory motion only O Simple harmonic motion O Will come to rest at centre O Will move on a circular path

Two positive charges q are placed on x axis at a 0 and a 0 Variation of electric field along x axis is drawn in graphical form taking electric field to be positive when its direction is along positive x axis Then choose correct graph a 0 a 0 q q x a x a x a O E E E O E x a X x a x a X

The electric field at a point inside a long cylinder charged throughout its volume is given by the relation E 3kr Where k is a positive constant and r is the distance from the axis of the cylinder Then choose the correct option s for the charge density p inside the cylinder which depends on ras A por B pxr C pxr D pxr 2

Consider the charge configuration and a Gaussian surface as shown in figure If 1 2 and are net electric flux due to charges 91 92 and 93 respectively then Here q1 92 and 93 all are different and non zero charges qi 0 03 0 2 0 93 Gaussian surface 0

2 A rod of uniform charge density and length Li placed vertically as shown A point charge Qo is placed at point O at a distance L from its one end Potential energy of charge Qo is equal to B A Q In 2 4780 Q In2 21TE0 20 480 20 2 080

Two bodies A and B having masses m and 2m respectively are kept at a distance d apart A small particle is to be placed so that the net gravitational force on it due to the bodies A and B is zero Its distance from the mass A should be 1 x d 1 2 2 x X d 1 4 3 x d 1 3 d 1 6 Find not force of gravitation 4 x

2 Two charges q and 3q are placed fixed on x axis separated by distance d Where should a third charge 2q be placed from q so that it will not experience any force q 1 3 d 3d 2 d 3d 2 d 2 4 d 3d 2 EEN PARK d 3d 2 NA

Two point charges are placed at the corners of a rectangle of sides 5 00 cm and 10 0 cm as shown below The charges are q 8 00 C and q2 5 00 C Take V and U to be zero at infinity a What is the electric potential energy of the two charges b What is the electric potential at point A c What is the electric potential at point B d How much work is done by an external agent to move a 1 2 0 C charge from A to B 91

Four point charges 20 20 Q and Q are fixed on the vertices of a square whose sides have length L as shown in figure The point O is the intersection point of diagonals of the squa 2KQ fifth point charge 4Q is slowly moved from infinity to point O The work done by external agent during this process is av Write va in OMR sheet 1 20

Three concentric conducting shells A B and C of radius a 2a and 3a respectively are given charge Q 2Q and Q If potential of shell B 1 then value of N is 4 TEO K 3a NKQ is 6a 2Q Q Answer a 2a A B C

Five point charges each of value q are placed on five vertices of a regular hexagon of side L metre Wha is the magnitude of the force on a point charge of value q coulomb placed at the centre of the hexagon A 1 q 4 L B10 B 4 o L C 19 4t E L D 1 q 4 E L E zero

icate departure from the inverse square law Example 1 11 The electric field components in Fig 1 27 are E ax E E 0 in which a 800 N C m2 Calculate a the flux through the cube and b the charge within the cube Assume that a 0 1 m Z a a a a

Two semicircular thin wires of radii R and R2 having same origin O are uniformly charged with charge density A and A2 as shown in the figure If the net field at O is zero when R 1 3 R2 then find the ratio A1 A2 O P

21 A semicircular wire of radius a having as charge per unit length is shown in the figure Find the electric potential at the centre of the semicircular wire a C 0 480 4TE OR d None of these b

40 Find the force of interaction of two dipoles if the two dipole moments are parallel to each other and placed at a distance x apart a 3P P2 4 E OX 0 7 P b P P2 4 EXA C P2 P P 4 EX 4 d P P2 3 EX 4

A point charge q is placed at centre of a hollow conducting sphere with radius R carrying a charge Q The potential at a point in a space at a distance r R from the centre of the sphere is A zero B C D Q q 4 4 0 Q q 4 o r R

39 What work must be done to rotate an electric dipole through an angle 0 with the electric field if an electric dipole of moment p is placed in an uniform electric field E with p parallel to E a W pE 1 cos0 c E 2pE 1 cos0 b W pE 1 cos0 d None of these

The electric field near the earth s surface is 44 N C downward An object of charge 10 2 C floats at rest near the earth s surface as shown in the figure Find the mass of the object in g Use g 10 m s Eearth Eearth m mg

A certain charge Q is to be divided in the ratio p q between two bodies which are located at a certain fixed distance from each other For the force of repulsion between them to be maximum the ratio p q should be A 1 1 B 1 2 C 1 4 D 1 6

A very long line of charge density 7 nC m is placed parallel to a very large sheet of charge denstiy a 4 nC m as shown in the figure Find the magnitude of the net electric field at the indicated point P between the line and the sheet KA 10 cm long line O O O large sheet 0 6 23 10 N C 6 83 103 N C 4 43 10 N C 5 03 103 N C 5 63 x 103 N C

corners of a square of side and a charge qo is ke at its centre so that whole system is in equilibriur The charge q is 1 90 11 2 2 2 9 1 2 2 2 do 11 2 21 4 011 251

34 A point charge Q is fixed above a large conducting sheet Select correct statement regarding electric field 1 Electric field is uniform in space upper and lower side of sheet Q 2 Direction of electric field lines on upper and lower fance of sheet are in opposite direction 2 Flo One Year Medical 2016 2017

An electric dipole of moment p is kept at the origin pointing along the z axis Given that z is much greater than the length of the dipole the potential difference between the point 0 0 z along its axis and a point on the equatorial plane x y plane is A B C P 2 4 Z D P 4 Z P 2 2 Z P

estion 2 Two point charges are located on the x axis The first is a charge q11 00 nC at x 0 500 m At what distance x in cm a second charge q2 1 8 nC should be placed so the net electric field at the origin is E 43 0 i N C 91 92 0 5m x X

An isolated conducting sphere of radius R has a positive charge Q Another uncharged conducting sphere of radius R 2 is brought in contact with the first one and then the two spheres are separated The charge that remains on the first sphere is A Q 3 B 2 Q 3 C 3 Q 4 D 4 Q 3

37 When inner and outer concentric spheres as shown in figure have 20 C and 15 C charges potential difference between them is 40 V If charge on outer sphere is doubled potential difference between two spheres becomes n times the initial value The value of n is 1 2 3 1 b a 2 2 4 1 2

6 In the following four situations charged particles are at equal distance from the origin Arrange them the magnitude of the net electric field at origin in increasing order i iii 5q 2q 3q de de OX 4q 29 1 i iii ii iv 2 ii i iii iv 3 i ii iv iii 4 iv ii iii i OX ii iv 3q 2q 3q OX 9 OX q New Lig

33 A charge q is fixed near by two point charges Q each as shown The net force experienced by the charge is equal to 0 1 01 1 2Qq 2 4 EO 1 3Q Q 0 90 9 2 1 3Qq 4 EO 2 1 1 Zem

16 A uniform electric field of strength 60 V m exists in X Y plane making an angle 120 with positive x axis The potential difference between points P 2 3 anc Q 4 1 is given by 1 60 3 3 V 3 30 3 3 V 2 60 3 3 V 4 30 3 3 V

41 A charge q is kept midway between two charges C each on the line joining two charges The system of charges are in equilibrium if q is 1 q 3 9 Q 4 Q 2 52 2 9 4 9 1 2 4 5

charge of magnitude Q but positive and negative altemately as shown Then the electric field at centre of ring will be A kw B B R where 2k 3k Y D None of these where 1 3Q TR where 1848 TR

42 Two identical charged pendulums are inclined at angle 30 and 60 from infinite sheet of charge of surface charge densities o and o respectively as shown The ratio of o and o is CT 30 60

Two identical metallic spheres having charge 6Q and 2Q are placed r distance apart from their centres Force of attraction between them is F After that if they are brought in contact and then placed at the same distance r New force acting on them is a F 2 b F 3 c F 6 d F 4

8 A particle of mass m and charge q projected with a speed u at an angl e above the horizontal after travelling a horizontal distance xo enters region where in addition to gravity a uniform static horizontal electri field also exists Boundary of this region is vertical If after some time the particle returns to the point of projection find magnitude of th electric field and time of flight of the particle Acceleration of free fall g and influence of the air is to be neglected

charge q is placed outside it as shown in figure then incorrect statement is Di B conductor C q 1 Electric field at point A due to induce charges is zero 2 Electric field at point B due to the poi charge q is non zero 3 is negative 4 Electric potentials at A and B are same

41 Two metal spheres of radii R and 2R having some charge density o are brought in contac then charge densities becomes Dim 81m 20 3 50 50 a 2 2 810 810 20 a w wia

Two charge 6 C and 4 C are separated at distance 15 cm apart then the point on the line joining the charges where electric potential is zero is 1 At distance 6 cm from 6 C 2 At distance 45 cm from 6 C 3 At distance 30 cm from 6 C 4 At distance 60 cm from 6 C 30

37 A metal sphere of radius R is given a potential 37 V then energy stored inside the concentric sphere of radius 2R is 1 TE RV 3 2 RV 2 17 TE RV 4 4 RV

DE02 BOAHBO NCERT BASED OBJECTIVE PHYNELECTROSTATIC POTENTIAL CAPACITANCEP65 29 Curve A and B represents variation in el field and potential of a point charge ther E or V A B 1 A represents electric field 2 B represents electric field 3 Any of the curve may represent ele and potential 4 Can t be determined

charge then B 1 Sign of V V is negative B 2 Sign of work done by external agency in moving a negative charge from B to A is negative 3 Sign of work done by the field in moving a positive charge from A to B is positive 4 Sign of work done by the external agency in of 237 moving a negative charge from B to A is positive 1

5 Work done against electrostatic force in bringing a unit positive charge from infinity to a point is 1 Equal to the electrostatic potential V at that point 2 equal to the negative of work done by electrostatic forces 3 Both 1 2 4 Neither 1 nor 2 16 Uchi Felf 1 2

25 A small sphere of radius r having charge q is 25 r enclosed by a spherical shell of radius r having charge q Which charge will necessarily flow from the sphere to the shell when connected 1 9 2 9 4 May be q 3 both 1 and 2

8q 8q 3 W oq 4 Non Work done in moving a charge from one poi to the other inside a uniformly charge conducting sphere is 1 Always zero 3 May be zero 2 Non zero 4 None of these

If SW is the work done against electrostatic fo in bringing of a infinitesimal small test charge q fr infinity to a point P then potential at point P is SW SW

A hollow charged metallic spherical shell has radius R If the potential difference between its surface and a point at a distance 3R from the centre is V then the value of electric field intensity at a point at distance 4R from the centre is 1 3V 19R 2 V 6R 3 3V 32R 3V 16R

Given diagram can never represent 1 An electrostatic field 2 A magnetostatic field 3 Field for moving charge 4 An induced electric field Which of the following quantities depend

A and B are two concentric metallic shells If A is positively charged and B is earthed then electric B O 1 Field at common centre is non zero 2 Field outside B is non zero 3 Potential outside B is positive ositive 11 A

Two charged spheres of radii 10 cm and 15 cm are connected by a thin wire No current will flow if they have 1 The same charge on each 2 The same potential 3 The same energy 4 The same field on their surfaces

4 An electric dipole of dipole moment P is rotated in a uniform electric field of strength E from position of stable equilibrium to unstable equilibrium Then work done by external agent in this process is 1 Zero 2 PE 3 2PE 4 2PE