Electric Field and Potential Questions and Answers

The acceleration due to gravity at the north pole of Neptune is approximately 11 2 m s Neptune has mass 1 02 x 1026 kg and radius 2 46 x 10 km and rotates once around its axis in a time of about 16 h Part A What is the gravitational force on a 5 90 kg object at the north pole of Neptune Express your answer with the appropriate units Wap Submit Part B Value Request Answer d Units What is the apparent weight of this same object at Neptune s equator Note that Neptune s surface is gaseous not solid so it is impossible to stand on it

Two point charges are placed on the x axis The first charge q1q1q 1 12 00 nCnC is placed a distance 15 0 mm from the origin along the positive x axis the second charge q2q2q 2 4 00 nCnC is placed a distance 9 00 mm from the origin along the negative x axis An unknown additional charge q3q3q 3 is now placed at point B located at coordinates 0 mm 13 0 mm Find the magnitude and sign of q3q3q 3 needed to make the total electric field at point A equal to zero

Charges Q is uniformly distributed in each of three dielectric solid spheres 1 2 and 3 of radii R 2 R and 2R respectively as shown in figure If magnitudes of the electric fields at point P at a distance F from the centre of spheres 1 2 and 3 are E E2 and E3 respectively then P IR 1 2 3 R 2 Sphere 1 Sphere 2 E E2 E3 E3 E E2 E E2 E3 2R Sphere 3

A particle A of charge q placed near a uniformly charged infinite plane sheet with surface charge density a experiences a force f When this particle is placed near an infinite metal plate with surface charge density o it experiences a force f Then equals to 12 1 1 3 2 2 2 4 3

2 As one moves radially from infinity towards th centre of uniformly charged sphere electric fiel intensity will 1 Increase continuously 2 Decrease continuously 3 First decrease then increase 4 First increase then decrease W u

30 Three concentric spherical shells have radii a b and c a b c and have surface charge densities o and o respectively If V V and V denote the potentials of the three shells then for c a b we have 2009 a Vc V V B c V V V A C B A b Vc V VA d V V V B

Two charges q and q2 are placed 30 cm apart shown in the figure A third charge q is moved along the arc of a circle of radius 40 cm from C to D The change in the potential energy of the system is 2 3 CO 93 40cm 91 99293 4 89193 41 0 69193 4180 69293 30cm 92 B D

7 Write an expression for potential energy of an electric dipole placed in external electric field and explain the terms Wha

Five point charges are placed at the corners of a regular hexagon of side a as shown in figure Net force experienced by an electron placed at centre O will be q 5q 1 2 3 4 6kqe a 29 3kqe a 6kge a 3kge a 29 towards 5q charge towards 3q charge towards 3q charge towards q charge 39

A point charge q moves from point P to point S along the path PQRS figure in a uniform electric field E pointing parallel to the positive direction of the X axis The co ordinates of the points P Q R and S are a b 0 2a 0 0 a b 0 and 0 0 0 respectively The work done by the field in the above process is YA S 1 qEa 3 qEa 2 P R 2 qEa 4 qE 2a b

A particle of charge q mass m moves in a circle of radius r around an infinitely long line charge of linear charge density Then time 1 4780 period will be K 2 T m 1 T 2 2 2kaq 3 T 4 I 9 9 4x m 2kaq 2 V m 2khq m V2kxq

25 The electric field at 2R from the centre of a uniformly charged non conducting sphere of radius R is E The electric field at a distance from the centre will be 2 1 Zero 3 4E 2 2E 4 16E

Three point charges are lying as shown Surface shown is imaginary gaussian surface then find correct option q zero 9 9 1 Field at each point of gaussian surface is 2 Field is due to q2 only 3 Field is due to all three charges 4 Field is uniform at the gaussian surface

a 56 The electric field intensity Espe shown arrangement are in the ratio R 1 1 2 2 9 a P 3q 2r Q Fig Hollow concentric shell 2 2 1 4 4 3 al 47623456

13 Two equal point charges A and B are R distance apart A third point charge placed on the perpendicular bisector at a distance d from the centre will experience maximum electrostatic force when R 1 d 2 2 3 d R 2 R 2 d 1 2 4 d 2 2R

A ring of radius R has charge Q distributed uniformly over it A charge q is placed at the centre of the ring such that electric field becomes zero at a point on the axis of the ring distant R from the centre of the ring The value of charge q is 1 ol olm 3 3 RI R 2 9X R P 2 2 4 3 4 V3 ol

2 Four electric charges A B C D are arranged as shown The electric force will be least between charges A y 2 C 4 C D A A and B C B and D X B D 4 C 2 C B C A and D A and C

The spatial distribution of the electric field due to two charges A and B is shown in figure Which one of the following statements is correct 1 A is ve and B is ve and A B 2 A is ve and B is ve and A B 3 Both are ve but A B 4 Both are ve but A B Q

4 160 V If potential at a point P 1 1 1 is given by the 35 relation V x y 2z then calculate the electric field at P 1 21 21 2k 2 21 2j 2k 3 21 25 2k 4 21 21 2k 4 160 V af fara P 1 1 1 V x y 2 ART AGRI 1 21 2j 2k 2 21 2j 2k 3 21 21 2k 4 21 2j 2k

Two point charges Q Q are fixed at x 0 and x a Assuming that field strength is positive in the direction coinciding with the positive direction of x E x 0 X a X then which following option will be correct 1 Both Q and Q are negative with Q Q 2 Q is positive and Q is negative with Q Q l 3 Q is negative and Q is positive with Q Q l 4 Both are positive Q Q l

A charge of luC is divided into two parts such that their charges are in the ratio of 2 3 These two charges are kept at a distance 1 m apart in vaccum Then the electric force between them in N is 1 0 216 3 0 0216 2 0 00216 4 2 16

3 20 cos e 5 The pulleys and strings shown in the figure are smoot and of negligible mass For the system to remain in librium the angle 0 should be equi 1 0 3 45 ath m Tatry m mg 2 30 4 60 lides down along the inclined wall

Two equal positive charges Q are fixed at points a 0 and a 0 on the x axis An opposite charge q at rest is released from point 0 a on the y axis The charge q will 1 Move to infinity 2 Move to origin and rest there 3 Undergo SHM about the origin 20 A particle of moving arou of radius r 16m q

EQ 4 Zero Suppose that a planet has a surface charge 34 density of 1 electron m given radius of the planet is 8850 km then calculate potential of the planet due to this charge 1 0 16 V 2 160 V 3 0 16 V 4 160 V 4 3 4 HIG EQ 1 g m t 8850 km 1 0 16 V 2 160 V 3 0 16 V a to 4 160 V

ring of radius R carries a charge q unimly distributed over it A long thin wire carrying charge per unit length is held along its axis with one end coinciding with the centre of the ring Find the interaction between the ring and the thread A q2 C 28 R 4qh TER R B 292 ne R D q 4xe R

J The grid each square of 1 mx 1 m represents a region in space containing a uniform electric field If potentials at point O A B C D E F G H are respectively 0 1 2 1 2 0 1 1 and 0 volts Find the electric field intensity y D C G H E F A 01m 1 V m 3 i j V m BX 2 1 1 V m 4 1 V m

Two uniformly charged non conducting hemispherical shells each having uniform charge density and radius R form a complete sphere not stuck together and surround a concentric spherical conducting shell of radius R 2 If hemispherical parts are in equilibrium then minimum surface charge density of inner conducting shell is A 2 o C o D 20 B G 2

22 Atlipule hay ng dipole norment p is placed in front of a solid uncharged conducting sphere as shown in the diagram The nel potential at paint A lying on the surface of the sphere is kp cos C zcro 22 Thron B D EPERT kpcos pad 9 re 2kp cos

Figure shows a charge array known as an electric quadrupole For a point on the axis of quadrupole obtain the dependence of potential on r for r a 1 and contrast your results with that due to an electric dipole and an electric monopole l e a single charge A a BC a q D P 9 9 9 P

a Deduce the expression for the torque acting on a dipole of dipole moment in the presence of a uniform electric field E b Consider two hollow concentric spheres S and S2 enclosing charges 20 and 4Q respectively as shown in the figure i Find out the ratio of the electric flux through them ii How will the electric flux through the sphere S change if a medium of dielectric constant e is introduced in the space inside S in place of air Deduce the necessary expression 4Q 2Q S S

ph sphere has radius r If the A hollow charged me potential difference between its surface and a point at a distance 3r from the centre is V then the electric field intensity at distance 3r from the centre is 1 3r V 6r 2 4 2r igure shows a magnitude and in the region 3 Two concentric hollow conducting spheres of radius 12 Pare shown The charge on outer shell is shore so

A 2 0 m long metallic rod is rotated with an angular velocity of 200 rad s about an axis normal to the rod passing through its one end A constant and uniform magnetic field of 0 25 T parallel to the axis exists everywhere The emf developed across the ends of the rod is 50 V 100 V 200 V Zor

An infinite large uniform charged non conducting sheet having surface charge density a is placed in an external uniform electric field E Figures shows electric field lines near the sheet Magnitude of electric field in left side of sheet is 4 N C and electric field in right side of the sheet is at angle tan 2 from sheet What is magnitude of uniform external electric field Sheet A 4 N C C 2 2 N C 4 N C AL B 5 N C D 4 2 N C a tan 2

28 Two resistances 102 and 152 are connected in series A cell of e m f 1 5V of negligible resis tance is connected between their ends Then a current flowing through 150 resistance is 60mA b P d across 10 resistance 0 9V c P d across 150 resistance is 0 9V d resultant resistance is 652 1 a and c are true 2 b and d are true 3 a and d are true 4 b and c are true

Inside a spherical uncharged conducting shell centered at O a point charge qis kept such that OA d The radii of the inner and outer surfaces of the shell are r and R The potential at point B is 1 Kq R d R d q B 2 okv Kq R Ka R D RA ww KON

Every resistance of the circuit given in Fig 2 81 has been expressed in the unit of ohm If the resistance of the volt meter is 90 what will be its reading 7 3 ww 1 15 1 W 9 30 13 24 V 27 Fig 2 81 10 14 7 7 V

Two large charged plane sheets of charge densities to and 20 Cm 2 are arranged vertically with a separation of d between them Deduce an expressions for the electric field at points i to the left of the first sheet ii to the right of the second sheet and iii between the two sheets

A charge q 2 2 uC is placed at the point P shown below What is the force on g in N Assume the positive direction is to the right Indicate the direction with the sign of your answer 3 2 m 1 6 m

the potential difference between two pol Work Potential difference x charge 0 x charge 0 scalar or vector and why Q 18 Derive an expression for electric potential due to a point charge C origin O Potential at P has to be found

131 In a potentiometer whose wire resistance is 1022 the potential fall per cm is V volts To reduce it to V 4 V cm the resistance that must be connected in series with the potentiometer wir is 1 402 2 302 3 20 2 4 102

22 A positively charged ball hangs from a long silk thread Electric field at a certain point at the same horizontal level of ball due to this charge is E Let us put a positive test charge q at this point and measure F q on this charge Then E a Flq b Flq

5 Variation of electrostatic potential along the x direction is shown in figure The correct statement about electric field is 1 x component at point B is maximum 2 x component at point A is toward positive x axis 3 x component at point C is along negative x axis 4 x component at point C is along positive x axis A B C X

A circular coil carrying current of single turn of radius R and mass 1 kg is hanging by two ideal strings as shown in figure When a constant mag field B is set up in the horizontal direction as shown then the ratio of tension 7 2 in strings will become P 3 find value of P Given R T T B g 4BI

A simple bar magnet hangs from a string as in figure A uniform magnetic field B directed horizontally to the right is then established Which of the pictures in figure does not show the equilibrium orientation of the bar magnet A Z B N S N C Z D N S

Projectile Above a Charged Sheet From the surface of a large uniformly charged sheet of surface density Coul m2 an electron is projected at an angle 45 from the surface of sheet from point A at speed u If it hits the sheet at point B calculate distance AR Neglect gravit

The acceleration of an electron due to the attraction between the electron and a proton when they are 1 6 A apart is m 9x10 31 kg e 1 6 10 19 C 1 Take 9 10 Nm C 2 4 TEO 1 1025 m s 3 1023 m s NEET 2020 Phase 2 2 1024 m s 4 1022 m s

A particle q 8 mC m 6 g has a velocity of 43 m s when it enters a region where the electric field has a constant magnitude of 99 N C and a direction that is the same as the velocity of the particle What is the velocity of the particle 4 s after it enters this region From your answer without a decimal place

ever cross each other Reasoning Electric field at a point supe rimpose to give on resultant electric fiel d a both are true and reason is correct e xplanation of assertion b both are true and reason is not corre ct explanation of assertion c Assertion is true but Reasoning is in correct d Assertion is incorrect but Reasoning is correct el both are incorrect

The negative charge q2 is fixed while positive charge q as well as the conducting sphere S is free to move If the system is released from rest 92 9 1 Both S and q move towards left 2 q moves towards right while S moves towards left 3 q remains at rest S moves towards left 4 both a and S remain at rest

A rod AB of length L is non uniformly charged with a linear charge density which depends on distance x from end A of rod as Cx Coul m Find electric field strength due to this rod a distance r from point B along the axis of rod