Electric Field and Potential Questions and Answers

One metallic sphere A is given positive charge whereas another identical metallic sphere B of exactly same mass as of A is given equal amount of negative charge Then Mass of A and mass of B still remain equal Mass of A increases Mass of B decreases Mass of B increases and of A decreases

A uniform electric field is present in X Yplane Due to electrostatic field electric potentials of point A 2 m 2 m B 2 m 2 m and C 2 m 6 m are 4 V 10 V and 16 V respectively The electric field is V m 3 2j 31 6j 2 4i 6j 51 6j 2

A proton of mass m approaches from very large distance towards a free proton with velocity vo along straight line joining their centres The distance of closest approach of tw protons is e 2Emv 8 TEMV e TE MV

The number of electrons present in 8 C of charge is 5 0 1018 10 0 1018 5 0 1019 10 0 1019

Shown in the figure is a shell made of a conductor It has inner radius a and outer radius b and carries charge Q At its centre is a dipole pas shown In this case Main 2019 12 Argil I P Choose only 1 answer A Surface charge density on the inner Q 2 surface is uniform and equal to

Two concentric spheres of radii 1 m and 2 m have similar charges with equal surface densities o The electric potential at the common center is 30 blow 20 ola

q Three charges each of magnitude q are placed at the corner of an equilateral triangle of side a the electrostatic force on each charge will be 9 q 4 a N 39 4 8a 2q 4 a Zora nr 9 min

Electric Potential at the Edge of a Disc Calculate the electric potential due to a uniformly charged conducting circular disc at a point lying at the edge of disc Surface charge density on disc is o cou x 8 5 Coul n

Two identical conductors of copper and aluminium are placed in an identical electric field The magnitude of induced charge in the aluminium will be O Zero Greater than in copper Equal to that in copper Less than in copper

For a dipole having magnitude of charge q 4 10 6 C and distance between the charges d 0 02 m If this dipole is placed in a electric field E 2 x 105 N C Then maximum torque on the dipole will be 1 6 x 10 Nm 3 2 x 10 2 Nm 2 4 x 10 2 Nm hr mir 4 8 x 10 2 Nm

wo very small spheres having charge Q and Q face each other at a certain distance between them If a dielectric having dielectric constant Kinserted between them then electrostatic force between them Increase Decrease Remains same Becomes zero The displacement of charge 2 C in the electric field E 21 3j k N C is 7 1 1 2k m The work done is 2 J 6 J 8 J 4 J

The ratio of electric potential due to a short electric dipole at point A whose position vector w r t centre of dipole makes 60 angle with direction of dipole moment to that at point B on axial position is Both points are at same distance from the center of the dipole 1 3 1 1 1 2

35 180 Mark for Review The displacement of charge 2 C in the electric field E 21 3 k N C is r 2k m The work done is 2 J 6 J 02 35 hr mi 8 J

30 180 7 2 J Two positive point charges of 10 C and 4 C are 10 cm apart The work in bringing them 5 cm closer is 2 4 J 4 8 J Mark for Review 3 6 J 02 3 hr m

50 180 An electron of mass m and charge e accelerated from rest through a potential difference Vin vacuum The final speed of electron will be m lev m 2e V m Mark for Review 2e V m

e angle between the dipole moment and ctric field at any point on the equatorial point 90 45 0 180 The potential on the surface of hollow spher radius 2 m is 200 volt The potential at 1 m f the centre of the sphere is 100 volt 200 volt 400 volt Zero

Eight charged water drops each with a radius of 10 mm and a charge of 10 pico Coulomb merge into a single drop The potential of this single drop is 3 6 V 45 V 36 V 4 5 V

Equipotential surfaces associated with an electric field which is along y direction are Planes parallel to xz plane Planes parallel to xy plane Planes parallel to yz plane Coaxial cylinders of increasing radii along the y axis

41 180 Mark for Review The value of electric permittivity of free space is 9 x 10 NC m 8 85 x 10 12 C2 Nm 8 85 x 10 12 Nm C 02 34 hr mi 9 x 109 C Nm

The electrical potential at a point x y z is given by V x y xz 4 The electric field Eat that point is 2xy z i x 3xz k 2xy x y j 3xz y k z i xyzj 3 k 2xy z i xy j 3z xk

15 Two charges of 25 x 10 coulomb and 25 x 10 coulomb are placed 6 m apart Find the electric field intensity ratio at points 4 m from the centre of the electric dipole 1 on axial line ii on equatorial line 0 1000 49 49 500 49 49

Three charges each of q are placed at the vertices of an equilateral triangle The charge needed at the centre of the triangle for the charges to be in equilibrium is A C 3q B 3 D

1 250 C 2 600 C 3 Four condensers each of capacity 4m F are connected as shown in the figure If Vp Vo 15 volt the energy store in the system is

Two isolated charged metallic spheres of radii R and R having charges Q and Q respectively are connected to each other then there is 1 No change in the electrical energy of the system 2 An increase in the electrical energy of the system 3 Always a decrease in the electrical energy of the system 4 A decrease in electrical energy of the system until Q R Q R potential of 300 volts Area of the plates is 100 cm and spacing

0 Two identical thin rings each of radius 10 cm carrying charges 10 C and 5 C are coaxially placed at a distance 10 cm apart The work done in moving a charge q from the centre of the first ring to that of the second is a c 9 STEO 9 ATTEO 2 1 2 2 1 2 b d 9 STEO 9 4RE0 2 1 2 2 1 2

Three charges each of magnitude q are placed at the corner of an equilateral triangle of side a the electrostatic force on each charge w be q q 4 a 3q 4 8 2q 4 e a

3 Consider a hollow spherical conductor that has a potential of 300 volts at its outside surface The potential inside the hollow space must be a Zero at the center and rising to something less than 300 V at the edge of the hollow space b Zero at the outer part and rising to 300 volts at the center c It depends on the ratio of outer and inner radii d Zero everywhere e 300 V everywhere f 150 V everywhere

There is uniform electric field of 8x10 N C What is the net flux in SI units of the uniform electric field through a cube of side 0 3 m oriented so that its faces are parallel to the coordinate plane 0 3 x 8 x 103 1 2 x 8 x 103 3 Zero 2 4 8 x 106 x 6

istration 37 The two conducting spherical shells shown in figure are joined by a conducting wire and disconnected after the charge stops flowing Find out the charges on each sphere after that 2R 8

Force of attraction between two point charges Q and Q separated by d meter is Fe When these charges are given to two identical spheres of radius R 0 3 d whose centres are d meter apart the force of attraction between them is 1 Greater than Fe 2 Equal to Fe 3 Less than Fe 4 None of the above

A charge q is distributed over two concentric hollow conducting spheres of radii a and b b a such that their surface charge densites are equal The potential at their common centre is 1 Zero 3 9 4 E La b 9 q a b 2 A a b ak qa G kaa 0 9 a b 4 4 a b 2

Two charges 2 C and 8 C are placed at two vertices of equilateral triangle of side 1 m The potential at third vertex of the triangle is NCERT Pg 57 1 90 x 103 V 2 9 103 V 3 0 9 103 V 4 900 x 10 V

12 An infinite plane sheet of positive charge has surface charge density o A metallic ball of mass m and charge Q is attached to a thread and is tied to a point A on the sheet PQ The angle e made by the string with the plane sheet is in equilibrium is b tan Qo 48 mg Qo E ma a zero c tan Qo 2 mg d tan

5 Find the expression for the torque experienced by an electric dipole placed in a uniform electric field Question 16 Find the expression for the potential energy of a system comprising of three point charges q q and 93 placed respectively at the three vertices of an equilateral triangle having length r OR

Two infinitely charge sheets having charge density and 20 as shown in the figure The electric field at the point P will be G 20 O 280 30 280 View in y a

English Two very small spheres having charge Q and Q face each other at a certain distance between them If a dielectric having dielectric constant Kinserted between them then electrostatic force between them O Increase O Decrease O Remains same Becomes zero View in

What is the force between two small charged spheres carrying charges 3 x 10 C and 4 x 10 C placed 40 cm apart in air Question 4 2

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 O 500 V m O 1000 V m O 2000 V m View in 1500 V m

tensity at the end on position of an electric dipole Question 14 3 A charged oil drop weighing 1 6 x 10 5 N is found to remain suspended in a uniform electric field of intensity 2 x 10 N C Find the charge on the drop Question 15 Find the expression for the torque experienced by an electric dinole placed in a uniform electric figold 3

A ring of radius r has given a charge Q and uniformly distributed over its length If a charge q is placed at the centre The electric potential energy of the charge q will be kqQ kqQ r kg Q r

English Four charges 1 C 2 C 3 C and 4 uC are placed at 1 m 2 m 3 m and 4 m from origin The net electric potential at the origin will be O 9 KV O 18 KV 36 kV Zero View in

Two concentric uniformly charged spheres of radius 10 cm 20 cm are arranged as shown in the figure Potential difference between the spheres is 1 4 5 x 1011 V 2 2 7 x 1011 V 3 O 4 none of these 10C 10cm 20cm 20C

D A nonconducting sphere of radius 10 cm is charged uniformly with a density of 100 nC m What is the magnitude of the potential difference between the center and a point 4 0 cm away 12 V 6 8 V C 3 0 V d 4 7 V 22V a b

9 The electric potential V at any point x y all in metres in space is given by V 4x volt The electric field at the point 1 m 0 2 m in volt metre is a 8 along negative X axis c 16 along negative X axis b 8 along positive X axis d 16 along positive Z axis

Let us plac shown in at M due identical conducting plate N parallel to it such that charge is induced on plate N a e If V is the potential at M due to induced negative charge on N and V is the potential Huced positive charge on N then The Q C Q V V V V Since V V as the induced negative charge lies closer to the plate M in comparison to induced positive C C Further if N is earthed from the outer side see figure then V V V the entire ositive charge flows to the earth harge C Q V Q V V C C M DO

Magnetic field intensity is defined as Magnetic moment per unit volume 2 Magnetic induction force acting on a unit magnetic pole Number of lines of force crossing per unit area 4 Number of lines of force crossing per unit volume

Charge is uniformly distributed with volume charge density p inside a very long cylinder of radius R If the potential difference between the surface and the axis of cylinder is PR n o find the value of n

29 A charged particle is placed at the centre of cube o length L ABCDEFGH Another same charge q is placed at a distance L from O Then the electric flux through ABCD is gen F Eo 0 60 E q C L q

Three equal negative charges of magnitude 9 each are at the vertices of an equilateral triangle of side d How much work will have to be done by an external agency to arrange the charges into a configuration in which the three charges are at the vertices of an equilateral triangle of side 2d A B C D 3q 8 d A 3q 8 d 6q 4 d 6q

Consider a uniform spherical charge distribution of radius R centred at the origin O In this distribution a spherical cavity of radius R2 centred at P with distance OP a R R see figure is made If the electric field inside the cavity at position is E F then the correct Ri statement s is are A E is uniform its magnitude is independent of R but its direction depends on r B E is uniform its magnitude depends on R and its direction depends on C E is uniform its magnitude is independent of a but its direction depends on a D E is uniform and both its magnitude and direction depend on a