Electric Field and Potential Questions and Answers

Charges q and q are placed at points A and B respectively which are a distance 2L apart C is the midpoint between A and B The work done in moving a charge Q along the semicircle CRD is AIPMT Prelims 2007 A qQ 1 6EL qQ 2 EL 3 C R B 2 4 D qQ 4 E L qQ 2 L

Two metal spheres one of radius Rand the other of radius 2R respectively have the same surface charge density o They are brought in contact and separated What will be the new surface charge densities on them NEET 2019 Odisha A B 01 01 53 5 6 02 0 02 56 5 2 5 5 O O O C

Two small balls having equal positive charge Q on each are suspended by two insulating strings of equal length L from a hook fixed to a stand The whole set up is taken inside a satellite The angle between the strings and the tension in each of them are respectively given by a 180 c 180 Q 12ne L Q 16 E L b 120 d 90 Q 16ne L Q 16ne L

B Figure shows track of three positive charged particles through uniform electric field E All charges are equal in value Which charge particle has more initial kinetic energy on entering horizontally between the plate NCERT Pg 47 1 2 3 1 1 u 1 Particle 1 2 Particle 2 3 Particle 3 Plate Plate

3 An infinite long straight wire has linear charge density 4 x 105 C m 1 The electric force experienced by a proton at perpendicular distance of 10 mm from axis of wire is NCERT Pg 37 1 1 25 x 10 4 N 3 2 8 x 10 6 N 2 1 68 x 10 3 N 4 1 15 x 10 1 N

D In a region the potential is represented by V x y z 6x 8xy 8y 6yz where Vis in volts and x y z are in meters The electric force experienced by a charge of 2 coulomb situated at point 1 1 1 is AIPMT 2014 1 6 5N 3 24 N 2 30 N 4 4 35N

This section will have 15 questions Candidate can choose to attempt any 10 question out of these 15 questions In case if candidate attempts more than 10 questions fi considered for marking As shown in figure a wire s passed through cylinder of length t if I ampere current is passed through the wire for t second then electric flux related to cylinder will T 41

Potentiometer is considered as an ideal voltmete because of Low resistivity Low conductivity High sensitivity High resistivity Solution a

Three charges 4 42 and 9 are placed as shown in the figure The x component of the force on q is proportional to 91 A 92 b B 9 92 b D 92 feager to f 92 93 93 2 C 92 93 62 a Your Answer cos sin 0 1 BM 93 2 2 b 9 cos sin

magnetic A coil of resistance 100 and 1000 turns have the magnetic flux line of 5 5 x 10 4 Wb If ther flux changed to 5 x 10 Wb in 0 1 sec then the induced charge in coil is 1 50 C 2 5 C 3 2 C 4 20 C F

A thin metallic spherical shell contains a charge Q over it A point charge q is placed inside the shell at point T separated from the centre by distance a Anot point charge q is placed outside the shell at a distance b from the centre as shown in the adjacent figure Now select the correct statement s from the following q a R Electric field at the centre due to charge over outer surface of the shell is zero Electric field at the centre due to charge over outer surface of the shell is 91 4 0b b De q

Q39 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 500 V m B 1000 V m C 2000 V m D 1500 V m Answer D Solution

A particle with charge 5 0 x 10 5C and mass 1 mg is directly projected from a large distance towards a stationary charged ball of mC as shown in the figure The charged particle is projected with the speed 10 km s1 along a line which is at a distance of 1 m from the stationary charge Then the distance of closest approach is r in metre Find integral value of r 1 m

A spherical shell with inner radius a and outer radius b is made of conducting material A charge Q is placed at the centre of the cavity and a charge q is given to the shell If the electric potential is zero at infinite distance from the centre the potential at a distance R from the centre where a R bis A zero 1 B C D Q 4 E R 1 4 1 4 Q 9 R Q 9 b Q q a b R

A spherical conducting shell of inner radius r and outer radius r2 has a charge Q a If a charge q is placed at the centre of the shell then surfacecharge density on the inner and outer surfaces of the shell are Q q q 4 r and 2 b If a charge q is placed at the centre of the shell then surface charge density on the inner and outer surfaces of the shell are 9 and 2 9 2 4 r 2 4 r 9 4 r 2 4 r c If a charge q is placed at the centre of the shell then surface charge density on the inner and outer surfaces of the shell are Q q and 2 2 4 r d The electric field inside a cavity with no charge is zero if the shell is spherical and non zero if the shell has any irregular shape

o 0 In case it no response is typed selected Two charged spheres are kept at a finite centre to centre spacing as shown in the figure The force of electrostatic interaction between them is first calculated assuming them point like charges at their respective centres and then force is measured experimentally If the calculated and the measured values are Fe and Fm respectively which of the following conclusion can you certainly draw

In the arrangement of parallel plate capacitors each plate has area A and separation d between consecutive plates The equivalent capacitance between A and B is Aso d Then value of n is B K 5 A K 3 K 6

he resistance does not depend on the distance between the electrodes because The effective cross section area through which the current flows is proportional of the distance betwee the electrodes The resistivity of earth is very high There is no interaction between electrodes and earth The potential of earth is very high

45 4 Two identical conducting spheres fixed in space attract each other with an electrostatic force 0 108 N when separated by 50 0 cm center to center A thin conducting wire then connects spheres When the wire is removed the spheres repel each other with an electrostatic force 0 0360 N What were the initial charges on the spheres 5 Point charges A

initial speed v 9 55 x 10 m s into a region where a uniform Protons are projected projected with with an initial electric field E 720 N C is present as shown in figure The protons are to hit a target that lies at a horizontal distance of 1 27 mm from the point where the protons are launched Find a the two projection angles that result in a hit and b the total time of flight for each trajectory 4 Proton beam V 0 E 720 N C Target 1 27 mm

4 1 or 3 depends on values of Q and Q 28 A ring have total charge q Consider two cases Case I Charge is uniformly distributed Case II Charge is non uniformly distributed 4 1 3 fate 28 fefact faran fay Then Which is true for the electric field intensity at a point on the axis of ring 1 E 3 E E 2 E E 4 Can not say Z Case I Case II for at 1 E 3 E E m faxi farfaya 2 E E 4 l

Consider a uniformly charged hemispherical shell shown below Indicate the directions not magnitude of the electric field at the central point P and an off centre point P on the drumhead of the shell A C P B D

Three charges are released from rest on a smooth horizontal table from the situation shown in the figure What is the speed of charge 2q when its distance from charge q becomes double of its initial value A 3q 4 ma 29 M B a 3q 27 ma a q 2 ma D 4 ma

stions Two point charges 9 and 92 are placed along x axis at some separation one of the electric field line emanating from charge q is 92 along the curve as indicated in diagram If then find the value of 9 6x 1 3 Correct answer 9 X

Two point charges 9 and 92 are placed along x axis at some separation one of the electric field line emanating from charge q is along the curve as indicated in diagram If x then find the value of 9 6x 1 3 Correct answer 6 9

Point charges are fixed at the hour marks of a wall clock as shown If net dipole moment of the system is along the direction of hour hand then time shown by clock is O O 12 0 Clock 3 0 Clock 6 0 Clock

Consider a non conducting sphere of radius a carrying uniformly distributed charge q surrounded by a spherical shell of radius 2a The region between a srs 2a is filled with change density p C r where ris the distance from the centre If the magnitude of electric field in the region asrs 2a is constant then the magnitude of charge in the volume a srs 2a can be written as nq Find the value of n 2a

A charge 2Q is uniformly distributed over the volume of a sphere of radius R Two point charges Q are placed at a distance D apart symmetrically about the centre of the sphere as shown in the figure The distance D such that the repulsive force between the two positive charges can be exactly balanced by the presence of the negative volume charge is A R 2 B R C R 3 3 5 1 R R R 2Q Q D 1 postuad

charges with linear charge densities 2 2 and are placed in a plane as shown What is the electric field at point P 1 2 3 2k r 4k r 8k 3r 2 P 12 r12

Figure shows three concentric conducting spherical shells of radii a b and c c b a The innermost and outermost shell are given charges Q and Q respectively and the middle shell has been earthed Select the correct alternative s ba shell is Q 1 Q 1 The total charge on middle shell is zero 2 If IQ 1Q total charge on middle shell has opposite sign as that of Q 3 The charge on the outer surface of outermost b 02 1 6 C shell is Q2 4 The potential at a point outside the outermost I where r is distance from O b 1 Q C

In the figure A B C and D are four concentric spheres of radius a 2a 3a and 4a and contain charges 3 6q 6q and 12q respectively In the beginning switches S and S are open After earthing the sphere C Aq amount of charge flows from the sphere C to the earth If the sphere B is also earth then Aq2 amount of charge flows from the sphere B to the earth find the value of A 13 B C 4a IN Aq Aq 2

Electric Field 9 Four particles each having a charge q are placed on the four vertices of a regular pentagon T distance of each corner from the centre is a Find the electric field at the centre of the pentagon

1 nC 60 60 Consider the triangle of charges diagram for which d 2 cm q 2 nC and the x axis points to the right What is the force on the 1 nC charge Give your answer as a magnitude and a direction N 90 degrees counterclockwise from the x axis

22 Two charges of magnitudes 20 and Q are located at points a 0 and 4a 0 respectively What is the electric flux due to these charges through a sphere of radius Sa with its center at the origin

Consider an electric field E Eox where E is a constant The flux through the shaded area as shown in the figure due to this field is alovgronsoitonil od a 2E a b 2Ea c Ea Ea d 01 510lorib Z Hiw ca a 0 a xk a a a 0 0 0 0 a 0 y

ges each equal to q are kept at x a and x a on the X axis A particle of mass m and charge 90 9 2 is placed at the origin If charge qo is given a small displacement y a along the Y axis the net force acting on the particle is proportional to a y b y c 16

4 118 The work done in moving a charge 3 C from B to A is Take 1 4 100 Nm C 5 C A 5cm B 2 C 15cm 1 2 8 J 2 3 5 J 3 4 5 J 4 5 5 J

A point charge q is placed inside a neutral conducting spherical shell of inner radius 2R and outer radius 3R at a distance of R from the centre of the shell The electric 1 times potential at the centre of shell will be 4 q 2R 4q 3R 3 5q 6R 2q 3R

Two point charges q and q are of magnitude 2 C and 2 C respectively are placed 0 2 m apart as shown in figure The ratio of electric field at a point A to the point B will be 2 C B 0 2 m Options 32 3 4 IM 10 0 1 m 2 C

The figure shows an uneven arrangement of electrons e and protons p on a circular arc of radius r 1 90 cm with angles 0 30 0 2 40 0 03 38 0 and 04 34 0 What are the a magnitude and b direction relative to the positive direction of the x axis of th het electric field produced at the center of the arc a Number i b Number i P 8 8 Unit Unit N C P 8 degrees 0 P

Assertion Two large conducting spheres carrying charges Q1 and Q2 are brought close to each other The magnitude of electrostatic force between them is exactly given by Q Q 4ne r where r is the distance between their centers Reason Here charges Q1 and Q2 can be assumed to be concentrated at the centers of their respective spheres 1 Point

mple 10 Four charges are placed on corners of a square as shown in figure having side 10 cm If q is 1 C then what will be electric field intensity at the centre of the square B on Side 0 1 m a Half of diagonal 5 0 1 9 A D 29 c q 1 x 10 6 C 29 r J 31 0 b 1 2 Soc p Shot by Souradeep Manna

4 do hot form closed loop 5 Draw the electric field lines when a point charge q is kept near an uncharged conducting plate Tiels Short answer 5x2 10 6 Consider a uniform electric field E 3 X 10 i N C calculate the flux of this field through a square surface area 10 cm 7 Draw a equipotential surface due to point Q 0 8 Can two equipotential surfaces intersect each other Give reasons 9 Calculate potential on the axis of a ring due to charge Q uniformly distributed along the ring of radius R 10 Distinguish between dielectric and conductor

This section contains 35 SINGLE CORRECT questions Each question has 4 choices 1 Read More e work done by an external force to carry a po rge go from a point A to B on the same ipotential surface is distance between A and IV is potential of the equipotential surface O qv Phy Section A O qv 2 O2qV

39 An electric dipole is placed with its axis making an angle of 30 degrees with an electric field of strength 10 4 N C It experiences a torque of 10 2 N m 42 i Find dipole moment of the dipole Mark only one oval 282 8 x 10 4 C m 0 282 x 10 4 C m 2 828 x 10 4 C m 28 28 x 10 4 C m 43 ii Find potential energy of the dipole Mark only one oval 2 45 J 24 5 J 0 245 J 245 0 J 1 pc 1 pc

Two point charges Q are placed on the x axis d as shown in the figure A 2 d at x and X 2 third charge q is placed on the y axis such that the force on the charge q is maximum The distance of charge q from the origin is Value of n is AY d Jn

Consider three particles with positive charges Q 1C Q 2C and Qs 4C placed in vacuun Find the minimal possible magnitude of the force between Q and Q if you know that th force between Q and Q is F 2 8 N and the force between Q and Q is F 16N use 2 1 41 1 12 3 23

67 Six charges are placed at the vertices of a regular hexagon of side length a as shown in the figure The electric field on the line passing through centroid O and perpendicular to the plane of the figure at a distance x a from O is coll ho o noillcod 1 Q 3 Q Q Qa EO X blastedge a Q 2 glupe 5 SX and To sts R C torl 2Qa 3 E X TE 0 OWT

66 Six charges are placed at the corners of a regular hexagon as shown If an electron is placed at its centre O force on it will be Isita 9 2q B 1 Zero 3 Along DC 9 A C O F D 3q E 2q 2q 2 Along OF 4 None of these

parallel to each other as shown in figure Plates 2 and 4 are connected by a conducting wire and plate 1 is earthed by switch Sw Initially switch is open and charges Q Q 3Q and Q are given to plates 1 2 3 and 4 respectively Surfaces of plates are mentioned by S to Sg as shown in figure Sw 1 2 Q Q S S S 2d 3 4 3Q Q S S S Sa Read Less Consider the case when switch was open then final charges on the surfaces S4 and S7 will be respectively