Electric Field and Potential Questions and Answers

Two metal plates having a potential difference of 42 800 V are 2 cm apart It is found that a particle of mass 1 96 x 10 15 kg remain suspended in the region between the plates The charge on the particle must be e elementary charge 1 3e 2 4e 3 6e 4 8e Fiast 2 2 2 at frana faa faal 800 le 2 a f 1 96 10 5 kg fed tal a 1 3e 3 3 6e 2 4e 4 Ea 4 8e

charges and placed at a certain distance apart repel each other with a certain force They are brought in contact and then moved apart to a distance e pulsion between them increase 4 5 times in comparison with the intital value The ratio of the final charges of the balls is

There are two small uncharged spheres placed at a distance of 1 m from each other N number of electrons are transferred from one sphere to another The force between the spheres is now measured to be equal to 2 newton then the value of Nis YER TRU GIDI NEGA a Y M qu v as whaka gi 31 2 DRIER HI41 OPTIONS MARK FOR REVIEW CLEAR SELECTION OA 4 8 x 105 OB 6 1 x 10 OC 2 8 x 106 OD 9 3 x 1013 27

A charge 3nC is moved from a point A 5 0 0 to B 5 0 0 and a dipole of dipole moment p is placed at the origin of a Cartesia system with coordinates of the two charges as q 0 2 0 and a 0 2 0 Find the work done in the process

211 A body which was initially neutral is now positively charged Then its mass 6 SFIDRIG YI GIDI SI DE GEMI GO VAUG ARTHUR I OPTIONS MARK FOR REVIEW CLEAR SELECTION A B OC Slightly decreases Slightly increases Remains same THERE

Q 89 A point charge q is placed at a distance x from the centre of a conducting sphere of radius R x qo k X R S q R a How much charge will flow through the switch S when it is closed to ground the sphere b Find the current through the switch S when charge hore with velocity V

17 Two metal spheres of masses m and m are suspended from a common point by a light insulating strings of same length The length of each string is same The spheres are given positive charges q and q Figure A shows angles made by the strings with vertical are different where as for figure B same Then which of the following is possible fig A A For figure A m m and q 9 B For figure A m m and q q C For figure B m m and q q D For figure B m m and q q EVA JA 9 36 fig B HE

Q 33 Your Answer 2 V Option 1 2 V Option 2 V Option 3 2 V Option 4 4 V A solid conducting sphere having a charge Q is surrounded by an uncharged conducting hollow spherical 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 4 Q the new potential difference between the same two surfaces is Correct Answer V

In the figure two point charges of value 10 6 C and 10 6C are placed on the x axis at x 10 cm and x 10 cm as shown Calculate the electric intensity and potential at the points M x 0 y 10 cm and N 20 omt M 0 10 10 6C O 2 10 c N 30 0

Two equal point charges are fixed at x a and x a on the x axis Another point charge Q is placed at the origin The change in the electrical potential energy of Q when it is displaced by a small distance x along the x axis is approximately proportional to 1 X 2 x 3 x

This question contains statement 1 Assertion and statement 2 Reason Of The four choices given after the statements choose the one that best describes the two statements A Statement 1 is true statement 2 is false B Statement 1 is true statement 2 is true Statement 2 is the correct explanation of statement 1 C Statement 1 is true Statement 2 is true Statement 2 is not the correct explanation of statement 1 D Statement 1 is false Statement 2 is true 1 Statement 1 Assertion For a charged particle moving from point P to Point Q the network done by an electrostatic field on the particle is independent of the path connecting point P to paint Q Statement 2 Reason The net work done by a conservative force on an abiect moving along a closed logg is zero 1

A uniform electric filed exists only in x y plane When a student moves a distance 0 01 m along Oa line potential decreases by 0 02 V The magnitude of electric field is 2 5 V m When a student walks along OB line which is perpendicular to Oa line potential decreases The electric field in vector form is 45

A dipole of dipole moment po is placed at origin Direction of dipole moment is toward x axis Po Assuming potential energy of dipole is zero when plE COLUMN I A Energy of a dipole pi will be zero if it is placed at Pq B Torque on a dipole pj will be maximum if it is placed at S C y component of electric field is zero at VS D Torque on dipole pi will be zero at S COLUMN II p a 0 a 2 q a a 2 0 r a 0 0 s 0 0 a

C the charges just behind a given segment of wire which push them just the right way by repulsion D the charges ahead A battery of emf 10 volt and internal resistance 202 is connected to an external resistance 802 as shown in the figure PH 802 IN 10V 292 www HQ A Work done due to conservative electric field while a unit positive charge passes through battery from Q to P along the arrow is 8 Joule B Work done due to conservative electric field while a unit positive charge passes through battery from Q to P along the arrow is 8 Joule C Work done due to conservative electric field while a unit positive charge passes through 80 along the arrow is 8 Joule D Work done due to non conservative electric field while a unit positive charge moves from Q to P along the arrow is 10 Joule D Figure shows the net power dissipated in R versus the current in a simple circuit shown

Question 4 1 A rectangular frame of area 10 m2 is placed in a uniform electric field of 20 N C with normal drawn on the surface of the frame making 60 angle with the direction of field The electric flux through the frame is a 100 Vm b 200 Vm c 50 3 Vm d 100 3 Vm

A point electric dipole with dipole moment P is placed in the external uniform electric field whe strength is E with p parallel to E Then a Net force experienced by the dipole is zero b One of the equi potential surfaces enclosing the dipole forms sphere 1 3 c The radius of spherical equi potential surface is 4 d The radius of spherical equi potential surface is P E P V4TE E

A metal rod AB of length I rotates with a constant angular velocity w about an axis passing through O and normal to its length The magnitude of emf induced between ends A and B in the absence of external magnetic mL field is where m is mass and e is ke charge of electron Find K L Answer I 08 09 3L 4 01 02 03 04 05 06 07 0 01 02 03 04 05 06 07

9 Consider uniform charged shell of surface charge density s 380 SI units and a dipole of dipole moment P 2TE SI units Centre of the shell and the dipole lies at the origin and dipole moment vector is along x axis If the field at a point on x axis just over the shell is E and that at a point on y axis just over the shell is Find E E in N C Radius of shell 50 cm Z YA X

17 A small ball of mass 1 kg and charge uC is placed at the centre of a uniformly charged sphere of 1 radius 1 m and charg mC A narrow smooth horizontal groove is made in the sphere from centre to surface as shown in figure The sphere is made to rotate about its vertical 1 2 diameter at a constant rate of revolutions second Find the speed w r t ground in m s with which the ball slides out from the groove Neglect any magnetic force acting on ball per 10 Seko q R O

6 Consider equal and opposite uniformly charged large parallel plates with charge density of magnitude o A small charge q is moved along the rectangular path ABCDA where side AB x and side BC y Then the correct statement is 0 s Ems A atom 060 D 100009 A B positive and equal to O Isilnetoq sT 20 1 Work done by electric field along path AB is qox 0 2 Point A is at lower potential 3 Work done by electric field along path ABCDA may or may not be zero

A ring is made of a wire having a resistance Ro 12 Q Find the points A and B as shown in the figure at which a current carrying conductor should be connected so that the resistance R of the sub circuit between these points is equal 8 to Q2 3 A A 1 12 8 l2 B Correct Answer

A dielectric slab of dielectric constant k mass m thickness d and area L x L is hanging vertically in equilibrium under the influence of gravity and electrostatic pull of a capacitor connected to a battery of voltage V The capacitor has plates of area L x L and distance between plates is d The capacitor is half filled by the dielectric Suddenly a mass of m is attached to dielectric without any impulse on the system The slab falls off in time t Evaluate t in sec Take k 2 V 4 volts L 80 cm d 0 1 mm

Figure shows tracks of two charge particles in uniform electrostetic field Trajectory of which charge is more curved 9 92 1 9 3 Equal for both V V 2 92 4 None

Two concentric shells having radius R and 2R have charges A and B and potentials 2V and 3 2 V respectively Now shell B is earthed and let new charges be q and q B Then will be equal to 9A qB A 1 B A C 1 B D

19 A current carrying infinitely long current carrying wire as shown in figure The torque acting on the loop is 2 3 Hoiiza 2T 2 Hoza 2 i4 Holiza In 2 2T 1233 a a an

The potential energy of a particle of mass 4 5 kg moving in the x y plane is given by U 7x 24y J where x and y are given in metre If the particle starts from rest from the origin then the speed of the particle at t 2 s is 1 5 m s 3 17 5 m s 2 14 m s 4 10 m s ff U 7x 24y x y z af 2 1 5 m s 3 17 5 m s 2 14 m s 4 10 m s fa 8

The variation of the magnitude of the electric field with adial distance r due to a given configuration is depicted the accompanying figure The configuration could be A thick spherical conducting shell with a point charge at its centre B thick spherical dielectric shell with a point charge at its centre C conducting sphere with surface charge D two neutral concentric thin conducting shells with a point charge at the centre E r

A dipole having dipole moment p is placed in front of a solid uncharged conducting sphere as shown in the diagram The net potential at point A lying on the surface of the sphere is kp cos A k pcos B p C zero D 2kp cos

For a series RLC circuit R XL 2Xc The impedance of the circuit and phase difference between Vand will be 5R tan 2 5R 2 7 tan IN 2 5Xc tan 2 5R tan 1 2

In resonance state of LCR series circuit resonance frequency of circuit is f If the capacitance is made 4 times of initial value keeping inductance same then the new resonance frequency will be O ti O O times times times

Which one of the following curve best represent the variation of impedance Zwith the frequency fin series LCR circuit ZA ZA ZA ZA f f f

An electric dipole is placed at an angle of 30 with an electric field intensity 2 x 105 N C It experiences a torque equal to 4 N m The charge on the dipole if the dipole length is 2 cm is Piesmo NEET Phase 2 2016 2 2 mC 1 8 mC 3 5 mC

is carrying a charge q are Two positive separated by a distance d If F is the force of repulsion between the ions the number of electrons missing from each ion will be e being the charge AIPMT Prelims 2010 on an electron 1 4 Fd 2 e 2 4TE F 0 d

A 60 F capacitor is connected to a 110 V 60 Hz AC supply The rms value of current in the circuit is 2 5 A 2 1 A 3 1 A 3 5 A

of heat el plate e on the plates e plates T Ax Question 29 A spherical capacitor consists of two concentric spherical conductors held in position by suitable insulating supports see bolow figure Show that the capacitance of a spherical capacitor is given by Charge Q Charge Q 12 4180 112 11 12 where and r2 are the radii of outer and inner spheres respectively Solution From the figure it is clear that Q charge spreads uniformly on inner rfa C

O 7 5 cm A 20 eV electron is circulating in a plane at right angle to a uniform field of magnetic induction 2 10 4 Wb m2 The orbital radius of electron is nearly 04 cm O 9 cm T 35 cm hr min

1 Electric potential V in a region varies with x co ordinate as shown in figure If E E2 E3 and E4 are magnitude of fields for the shown regions then V volt 15 10 E E W E3 0 2 3 4 1 E E2 E3 E4 E 5 x m 2 E4 E3 E E

stion 32 Tan Consider an configuration A small test charge is placed at a null point i e where E 0 of the configuration Show that the equilibrium of the test charge is necessarily unstable Verify this result for the simple configuration of two charges of the same magnitude and sign placed a certain distance apart

Two wires A and B of same material having radii ratio 1 3 carry current in the ratio 1 1 The ratio of drift speed of electron in A and B is 09 1 O 3 1 O 1 1 r

Physics The graph shows the potential energy of an electric dipole that oscillates between 60 What is dipoles kinetic energy in J when it is aligned with the field 180 U J 2 N 0 90 Question Palette 180

3 100 C 4 75 C 25 The electric field in a certain region is TI potential at any point x y z in this region will potential is zero at A is a constant 2 2 Ax 3 A 2x 3A 2x 4 A 3x

Three charges are positioned on an X Y coordinate system A 40 0 nC charge is placed at the point 50 0 0 00 cm A 46 9 nC charge is placed at the point 0 00 20 0 cm A 23 7 nC charge is placed at the point 40 0 40 0 cm What is the electric potential at the origin of the coordiante system in units of volts

Three charges are positioned in a straight line on the x axis A 400 nC charge is placed at the point x 0 cm A 740 nC charge is placed at the point x 10 cm A 544 nC charge is placed at the point x 15 cm What is the potential energy of this system of charges in units of joules

What is the potential difference that is required to be applied between 2 parallel plates separated by a distance of 0 353 m to produce an electric field of magnitude 40 0 N C Give the answer as a positive number

Question 27 In a certain region of space electric field is along the direction throughout The magnitude of electric field is however not constant but increases uniformly along the positive Z direction at the rate of 105 N C m What are the force and torque experienced by a system having a total dipole moment equal to 10 7 C m in the negative Z direction

A 3 00x104 C charge q2 blue charge and a 9 00x104 C charge q1 red charge are positioned as shown in the diagram below How much work is done by external forces in moving a 4 72 C charge from point a to point c in units of joules 4 00 cm 12 0 cm q1 8 00 cm b 12 0 cm q2 4 00 cm

98 Two short electric dipoles are placed as shown The electrostatic energy of interaction between these dipoles is Ecose X KP 11 3C05 0 co 73 r V site 1 coro 3 2kP P Cote 3 196 2kP P Sine P bawo 0 2 2kP P Cose r3 looneo at 4kP P Cote

P 8V 2V 8V 10 V OV 6V There is no direction because the electric field is zero 4 V 4 V What best describes the direction of the electric field at position P in the above diagram

A charged particle Q is placed outside a hollow cone on the axis of a cone at a distance x from the centre of its base Electric flux linked with the slant surface of the cone due to the charge is Q R 3 m de in se 1 2 3 4

The switch Sw of the circuit shown in the figure is closed at t 0 i and i2 are the electric current in the branch containing two ideal inductors L and L2 respectively at a certain instant Choose the most appropriate statement A At t 0 just after the switch is closed di E di E and dt L dt L B At t 0 just after the switch is closed i 0 i 0 EL EL andi L L r L L r C After long time i D All the above E L moovisor L Sw