JEE Questions for Physics Electrostatics I Quiz 18 - MCQExams.com

A body can be negatively charge by
  • Giving excess of electrons to it
  • Removing some electrons from it
  • Giving some protons to it
  • Removing some neutrons from it
A total charge Q is broken in two parts Q1 and Q2 and they are placed at a distance R from each other. The maximum force of repulsion between them will occur, when

  • Physics-Electrostatics I-71941.png
  • 2)
    Physics-Electrostatics I-71942.png

  • Physics-Electrostatics I-71943.png

  • Physics-Electrostatics I-71944.png
One of the following is not a property of field lines
  • Field lines are continuous curves without any breaks
  • Two field lines cannot cross each other
  • Field lines start at positive charge and end at negative charges
  • They form closed loops
Three equal charges are placed on the three corners of a square. If the force between q1 and q2 is F12 and thatbetween q1 and q3 is F13, the ratio of magnitudes F12 / F13 is
  • 1/2
  • 2
  • 1/2

  • Physics-Electrostatics I-71952.png
ABC is a right angled triangle in which AB = 3 cm and BC = 4 cm and ABC = π / 2. The three charges +15,+12 and –20 e.s.u. are placed respectively on A, B and C. The force acting on B is
  • 125 dynes
  • 35 dynes
  • 25 dynes
  • Zero
Force of attraction between two point charges Q and –Q separated by d metre is Fe. When these charges are placed on two identical spheres of radius R = 0.3 d whose centres are d metre apart, the force of attraction between them is
  • Greater than Fe
  • Equal to Fe
  • Less than Fe
  • None of these
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
The force between two charges 0.06m apart is 5 N. If each charge is moved towards the other by 0.01m, then the force between them will become
  • 7.20 N
  • 11.25 N
  • 22.50 N
  • 45.00 N
Two charged spheres separated at a distance d exert a force F on each other. If they are immersed in a liquid of dielectric constant 2, then what is the force (if all conditions are same)?
  • F/2
  • F
  • 2F
  • 4F
Two point charges +3 µC and +8 µC repel each other with a force 40 N. If a charge of –5 µC is added to each of them, then the force between them will become
  • –10 N
  • + 10 N
  • + 20 N
  • –20 N
Electric charges of 1 µC, –1µC and 2µC are placed in air at the corners A, B and C respectively of an equilateral triangle ABC having length each side 10 cm. The resultant force on the charge at C is
  • 0.9 N
  • 1.8 N
  • 2.7 N
  • 3.6 N
Two small conducting spheres of equal radius have charges +10 µC and – 20 µC respectively and placed at a distance R from each other experience force F1. If they are brought in contact and separated to the same distance, they experience force F2 The ratio F1 to F2 is
  • 1 : 8
  • –8 : 1
  • 1 : 2
  • –2 : 1
Two charges each equal to 2 µC are 0.5m apart. If both of them exist inside vacuum, then the force betweenthem is
  • 1.89 N
  • 2.44 N
  • 0.144 N
  • 3.144 N
A solid conducting sphere of radius a has a net positive charge 2Q conducting spherical shell of inner radius b and outer radius c is concentric with the solid sphere and has a net charge –Q. The surface charge density on the inner and outer surfaces of the spherical shell will be
Physics-Electrostatics I-71967.png

  • Physics-Electrostatics I-71968.png
  • 2)
    Physics-Electrostatics I-71969.png

  • Physics-Electrostatics I-71970.png
  • None of these
Three charges each of magnitude q are placed at the corners of an equilateral triangle, the electrostatic force on the charge placed at the center is (each side of triangle is L)
  • Zero
  • 2)
    Physics-Electrostatics I-71972.png

  • Physics-Electrostatics I-71973.png

  • Physics-Electrostatics I-71974.png
Three charges are placed at the vertices of an equilateral triangle of side \'a\' as shown in the following figure. The force experienced by the charge placed atthe vertex A in a direction normal to BC is
Physics-Electrostatics I-71976.png

  • Physics-Electrostatics I-71977.png
  • 2)
    Physics-Electrostatics I-71978.png
  • Zero

  • Physics-Electrostatics I-71979.png

Physics-Electrostatics I-71981.png

  • Physics-Electrostatics I-71982.png
  • 2)
    Physics-Electrostatics I-71983.png

  • Physics-Electrostatics I-71984.png

  • Physics-Electrostatics I-71985.png
A body has –80 micro coulomb of charge. Number ofadditional electrons in it will be
  • 8 × 10–5
  • 80 × 10–17
  • 5 × 1014
  • 1.28 × 10–17
Two point charges placed at a certain distance r in air exert a force F on each other. Then the distance r\' at which these charges will exert the same force in a medium of dielectric constant k is given by
  • r
  • 2)
    Physics-Electrostatics I-71988.png

  • Physics-Electrostatics I-71989.png

  • Physics-Electrostatics I-71990.png
A charge Q coulomb is placed on a solid piece of metal of irregular shape. The charge will distribute itself
  • Uniformly in the metal object
  • Uniformly on the surface of the object
  • Such that the potential energy of the System is minimized
  • Such that the total heat loss is minimized
Five balls numbered 1 to 5 are suspended using separate threads. Pairs (1, 2), (2,and (4,show electrostatic attraction, while pair (2,and (4,show repulsion.Therefore ball 1 must be
  • Positively charged
  • Negatively charged
  • Neutral
  • Made of metal
Equal charges q are placed at the four corners A, B, C ,D of a square of length a. The magnitude of the force onthe charge at B will be

  • Physics-Electrostatics I-71993.png
  • 2)
    Physics-Electrostatics I-71994.png

  • Physics-Electrostatics I-71995.png

  • Physics-Electrostatics I-71996.png
The ratio of electrostatic and gravitational forces acting between electron and proton separated by a distance 5 × 10–11m, will be (Charge on electron = 1.6 × 10–19 C, mass of electron = 9.1 × 10–31 kg, mass of proton = 1.6 × 10–27 kg, G = 6.7 × 10–11 Nm2 / kg2
  • 2.36 × 1039
  • 2.36 × 1040
  • 2.34 ×1041
  • 2.34 × 1042
Two identical spheres carrying charges –9µC and 5µC respectively are kept in contact and then separated from each other. Point out true statement from the following. In each sphere
  • 1.25 × 1013 electrons are in deficit
  • 1.25 × 1013 electrons are in excess
  • 2.15 × 1013 electrons are in excess
  • 2.25 × 1013 electrons are in deficit
Four metal conductors having different shapes
1. A sphere
2. Cylindrical
3. Pear
4. Lightning conductor
are mounted on insulating stands and charged. The one which is best suited to retain the charges for a longer time is
  • 1
  • 2
  • 3
  • 4
Two positive ions, each carrying a charge q, are 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 on an electron)

  • Physics-Electrostatics I-72001.png
  • 2)
    Physics-Electrostatics I-72002.png

  • Physics-Electrostatics I-72003.png

  • Physics-Electrostatics I-72004.png
A ball with charge –50 e is placed at the centre of a hollow spherical shell which has a net charge of –50 e. What is the charge on the shell\'s outer surface
  • –50 e
  • Zero
  • –100 e
  • +100 e
If 1010 electrons are acquired by a body every second, the time required for the body to get a total charge of1 C will be
  • Two hours
  • Two days
  • Two years
  • 20 years
Four point charges –Q, –q, 2q and 2Q are placed, one at each corner of the square. The relation between Q and q for which the potential at the centre of thesquare is Zero is

  • Physics-Electrostatics I-72008.png
  • 2)
    Physics-Electrostatics I-72009.png

  • Physics-Electrostatics I-72010.png

  • Physics-Electrostatics I-72011.png
Two small spheres each carrying a charge q are placed r metre apart. If one of the sphere is taken around the other one in a circular path of radius r, the work donewill be equal to
  • Force between them × r
  • Force between them × 2 πr
  • Force between them /2 πr
  • Zero
Two charged spheres of radii 10 cm and 15 cm are connected by a thin wire. No charge will flow, if they have
  • The same charge on each
  • The same potential
  • The same energy
  • The same field on their surfaces
Theelectric potential V at any point O(x,y, z all in metres) in space is given by V = 4x2 volt. The electric field at the point(1m, 0, 2m) in volt / metre is
  • 8 along negative X-axis
  • 8 along positive X-axis
  • 16 along negative X-axis
  • 16 along positive Z-axis
A hollow metal sphere of radius 5 cm is charged so that the potential on its surface is 10V. The potential at the centre of the sphere is
  • 0V
  • 10V
  • Same as at point 5 cm away from the surface
  • Same as at point 25 cm away from the surface
If a unit positive charge is taken from one point to another over an equipotential surface, then
  • Work is done on the charge
  • Work is done by the charge
  • Work done is constant
  • No work is done
A uniform electric field having a magnitude E, and direction along the positive X-axis exists. If the potential V is zero at x = 0, then its value at X = +x will be
  • V(x) = +xE0
  • Vx = – xE0
  • Vx = +x2E0
  • Vx = – x2E0
Figure shows the electric lines of force emerging from a charged body. If the electric field at A and B are EA and EB respectively and if the displacement between A and B is r then
Physics-Electrostatics I-72021.png
  • EA< EB
  • EA= EB / r
  • EA= EB / r2
  • EA> EB
ABC is an equilateral triangle. Charges +q are placed at each corner. The electric intensity at Owill be
Physics-Electrostatics I-72022.png

  • Physics-Electrostatics I-72023.png
  • 2)
    Physics-Electrostatics I-72024.png
  • Zero

  • Physics-Electrostatics I-72025.png
In the electric field of a point charge q, a certain charge is carried from point A to B, C,D and E. Then the work done
Physics-Electrostatics I-72027.png
  • Is least along the path AB
  • Is least along the path AD
  • Is zero along all the paths AB, AC, AD and AE
  • Is least along AE
The magnitude of electric field intensity E is such that, an electron placed in it would experience an electricalforce equal to its weight is given by

  • Physics-Electrostatics I-72028.png
  • 2)
    Physics-Electrostatics I-72029.png

  • Physics-Electrostatics I-72030.png

  • Physics-Electrostatics I-72031.png
Three concentric spherical shells have radii a, b andc(a A, VB and VC denote the potentials of the three shells, then, for c = a + b, wehave
  • VC =VA≠ VB
  • VC =VB≠ VA
  • VC ≠ VB≠ VA
  • VC =VB= VA
Two parallel plates have equal and opposite charge. When the space between them is evacuated, the electric field between the plates is 2 × 105 V/m. When the space is filled with dielectric, the electric field becomes1 × 105 V/m. The dielectric constant of the dielectric material
  • 1/2
  • 1
  • 2
  • 3

Physics-Electrostatics I-72036.png

  • Physics-Electrostatics I-72037.png
  • 2)
    Physics-Electrostatics I-72038.png

  • Physics-Electrostatics I-72039.png

  • Physics-Electrostatics I-72040.png
The mean free path of electrons in a metal is4 × 10–8 m. The electric field which can give on an average 2 eV energy to an electron in the metal will bein units of V/m
  • 8 × 107
  • 5 × 10–11
  • 8 × 10–11
  • 5 × 107
If E is the electric field intensity of an electrostatic field, then the electrostatic energy density is proportional to
  • E
  • E2
  • 1/E2
  • E3
In figure +Q charge is located at one of the edge of the cube, then electric flux through cube due to +Q charge is
Physics-Electrostatics I-72044.png

  • Physics-Electrostatics I-72045.png
  • 2)
    Physics-Electrostatics I-72046.png

  • Physics-Electrostatics I-72047.png

  • Physics-Electrostatics I-72048.png
On rotating a point charge having a charge q around acharge Q in a circle of radius r. The work done will be

  • Physics-Electrostatics I-72049.png
  • 2)
    Physics-Electrostatics I-72050.png
  • Zero

  • Physics-Electrostatics I-72051.png
Two parallel metal plates having charges +Q and –Q face each other at a certain distance between them. If the plates are now dipped in kerosene oil tank, the electric field between the plates will
  • Become zero
  • Increase
  • Decrease
  • Remain same
The number of electrons to be put on a spherical conductor of radius 0.1 m to produce and electric field of 0.036 N/C just above its surface is
  • 2.7 × 105
  • 2.6 × 105
  • 2.5 × 105
  • 2.4 × 105
Two plates are 2 cm part, a potential difference of 10 volt is applied between them, the electric fieldbetween the plates is
  • 20 N/C
  • 500 N/C
  • 5 N/C
  • 250 N/C
The intensity of the electric field required to keep a water drop of radius 10–5 cm just suspended in air when charged with one electron is approximately
(g = 10 newton kg/ e = 1.6 × 10–19 coulomb)
  • 260 volt/cm
  • 260 newton /coulomb
  • 130 volt/cm
  • 130 newton /coulomb
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