JEE Questions for Physics Electrostatics I Quiz 6 - MCQExams.com

In the combination of capacitors shown in Fig., the potential difference across the plates of the capacitor A will be
Physics-Electrostatics I-70638.png
  • 4.8 V
  • 6 V
  • 1.2 V
  • 2.4 V
A capacitor C1 of capacitance 1 µF and capacitor C2 of 2µF are separately charged fully by a common battery. The two capacitors are then allowed to discharge through equal resistors. Then
  • The current in each of two discharging circuits is zero at t = 0
  • The currents in the two discharging circuits at t = 0 are equal but not zero
  • The currents in the two discharging circuits at t = 0 are unequal
  • Capacitor C1 loses 50% of its initial charge sooner than C2 loses 50% of its initial charge
A thin metal plate M is inserted between the plates of a parallel plate capacitor as shown in Fig. The new capacitance in terms of initial capacitance C is
Physics-Electrostatics I-70641.png
  • 2C
  • C/2
  • C
  • infinity
A capacitor of capacity C1 =1µF is charged to a potential of 100 V. The charging battery is then removed and it is connected to another capacitor of capacity C2 = 2µF. One plate of C2 is earthed as shown in Fig. The charges on C1 and C2 in steady state will

  • Physics-Electrostatics I-70643.png
  • 50μC, 50μC
  • Zero, zero
  • 100μC, zero
A 10 µF capacitor is charged to a potential difference of 50 V and is connected to another uncharged capacitor in parallel. Now the common potential difference becomes 20 volt. The capacitance of second capacitor is
  • 15 µF
  • 30 µF
  • 20 µF
  • 10 µF
In the given circuit with steady current, the potential drop across the capacitor must be
Physics-Electrostatics I-70646.png
  • V
  • V/2
  • V/3
  • 2V/3
Consider the situation shown in Fig. The capacitor A has a charge q on it whereas B is uncharged. The charge appearing on the capacitor B a long time after the switch is closed is
Physics-Electrostatics I-70648.png
  • Zero
  • q/2
  • q
  • 2q
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 electrical potential energy of Q, when it is displaced by a small distance x along the X- axis is approximately proportional to
  • x
  • x2
  • x3
  • x–1
Two identical capacitors have the same capacitance C. One of them is charged to potential V1 and the other to V2. The negative ends of the capacitors are connected together. When the positive ends are also connected, the decrease in energy of the combined system is

  • Physics-Electrostatics I-70650.png
  • 2)
    Physics-Electrostatics I-70651.png

  • Physics-Electrostatics I-70652.png

  • Physics-Electrostatics I-70653.png
A conductor having a cavity is given a positive charge. Then field strength E A , EB and EC at point A (within cavity), at B (within conductor but outside cavity) and C (outside conductor) will be

  • Physics-Electrostatics I-70655.png
  • 2)
    Physics-Electrostatics I-70656.png

  • Physics-Electrostatics I-70657.png

  • Physics-Electrostatics I-70658.png
A fully charged capacitor has a capacitance ‘C’. It is discharged through a small coil of resistance wire embedded in a thermally insulated block of specific heat capacity ‘s’ and mass ‘m’. If the temperature of the block is raised by ‘∆T’, the potential difference ‘V’ across the capacitance is
Physics-Electrostatics I-70659.png

  • Physics-Electrostatics I-70660.png
  • 2)
    Physics-Electrostatics I-70661.png

  • Physics-Electrostatics I-70662.png

  • Physics-Electrostatics I-70663.png
One plate of a capacitor is connected to a spring as shown in Fig. Area of both the plates is A. In steady state, separation between the plates is 0.8 d (spring was unstreched and the distance between the plates was d when the capacitor was uncharged). The force constant of the spring is approximately
Physics-Electrostatics I-70665.png

  • Physics-Electrostatics I-70666.png
  • 2)
    Physics-Electrostatics I-70667.png

  • Physics-Electrostatics I-70668.png

  • Physics-Electrostatics I-70669.png
An insulator plate is passed between the plates of a capacitor. Then current
Physics-Electrostatics I-70671.png
  • first flows from A to B and then from B to A
  • first flows from B to A and then from A to B
  • always flows from B to A
  • always flows from A to B
In the circuit shown in fig., charge stored in 4µF capacitor is
  • 20µC
  • 10µC
  • 40µC
  • 120µC
Capacitor A is charged to a potential of 100 V and capacitor B is charged to a potential of 75 V. What are the charges on A and B after key K is closed, Fig.?
Physics-Electrostatics I-70673.png

  • Physics-Electrostatics I-70674.png
  • 2)
    Physics-Electrostatics I-70675.png

  • Physics-Electrostatics I-70676.png

  • Physics-Electrostatics I-70677.png
A parallel plate capacitor has area of each plate A, the separation between the plates d. It is charged to a potential V and then disconnected from the battery. How much work will be done in filling the capacitor completely with a dielectric of constant K?

  • Physics-Electrostatics I-70679.png
  • 2)
    Physics-Electrostatics I-70680.png

  • Physics-Electrostatics I-70681.png

  • Physics-Electrostatics I-70682.png
Two capacitors C1 and C2 = 2 C1 are connected in a circuit with a switch between them as shown in fig. Initially, the switch is open and C1 holds charge Q. The switch is closed. At steady state, the charge on each capacitor would be
Physics-Electrostatics I-70684.png
  • Q, 2Q
  • 2)
    Physics-Electrostatics I-70685.png

  • Physics-Electrostatics I-70686.png

  • Physics-Electrostatics I-70687.png
Two identical capacitors 1 and 2 are connected in series to a battery as shown in Fig. capacitor 2 contains a dielectric slab of constant K. Q1 and Q2 are the charges stored in C1 and C2. Now, the dielectric slab is removed and the corresponding charges are Q1’ and Q2’. Then

  • Physics-Electrostatics I-70689.png
  • 2)
    Physics-Electrostatics I-70690.png

  • Physics-Electrostatics I-70691.png

  • Physics-Electrostatics I-70692.png
The charge given to any conductor resides on its outer surface, because
  • The free charge tends to be in its minimum potential energy state
  • The free charge tends to be in its minimum kinetic energy state
  • The free charge tends to be in its maximum potential energy state
  • The free charge tends to be in its maximum kinetic energy state
When the distance between the charged particles is halved, the force between them becomes
  • One-fourth
  • Half
  • Double
  • Four times
There are two charges +1 µC and +5µC respectively. The ratio of the forces acting on them will be
  • 1 : 5
  • 1 : 1
  • 5 : 1
  • 1 : 25
Under the influence of the Coulomb field of charge + Q, a charge –q is moving around it in an elliptical orbit. Find out the correct statement (s)
  • The angular momentum of the charge –q is constant
  • The linear momentum of the charge –q is constant
  • The angular velocity of the charge –q is constant
  • The linear speed of the charge –q is constant
Three concentric metallic spherical shells of radii R, 2R, 3R, are given charges Q1, Q2, Q3 respectively. It is found that the surface charge densities on the outer surfaces of the shells are equal. Then, the ratio of the charges given to the shells, Q1 : Q2 : Q3, is
  • 1 : 2 : 3
  • 1 : 3 : 5
  • 1 : 4 : 9
  • 1 : 8 : 18
The ratio of the forces between two small spheres with constant charge (a) in air (b) in a medium of dielectric constant K is
  • 1 : K
  • K : 1
  • 1 : K2
  • K2 : 1
A soap bubble is given a negative charge, then its radius
  • Decreases
  • Increases
  • Remains unchanged
  • Nothing can be predicted as information is insufficient
Four charges are arranged at the corners of a square ABCD, as shown in the adjoining figure. The force on the charge kept at the centre 0 is
Physics-Electrostatics I-70698.png
  • Zero
  • Along the diagonal AC
  • Along the diagonal BD
  • Perpendicular to side AB
A charge Q is placed at each of the opposite corners of a square. A charge q is placed at each of the other two corners. If the net electrical force on Q is zero, then Q/q equals

  • Physics-Electrostatics I-70699.png
  • 2)
    Physics-Electrostatics I-70700.png
  • 1

  • Physics-Electrostatics I-70701.png
A body can be negatively charged by
  • Giving excess of electrons to it
  • Removing some electrons from it
  • Giving some protons to it
  • Removing some neutrons from it
The charge q is projected into a uniform electric field E, work done when it moves a distance Y is
  • qEY
  • 2)
    Physics-Electrostatics I-70703.png

  • Physics-Electrostatics I-70704.png

  • Physics-Electrostatics I-70705.png
Energy associated with a moving charge is due to a
  • Electric field
  • Magnetic field
  • Both electric field and magnetic field
  • None of the above
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

  • Physics-Electrostatics I-70707.png
  • 2)
    Physics-Electrostatics I-70708.png

  • Physics-Electrostatics I-70709.png

  • Physics-Electrostatics I-70710.png
Two identical conducting spheres carrying different charges attract each other with a force F when placed in air medium at a distance `c1\' apart. The spheres are brought into contact and then taken on their original positions. Now the two spheres repel each other with a force whose magnitude is equal to that of the initial attractive force. The ratio between initial charges on the spheres is

  • Physics-Electrostatics I-70712.png
  • 2)
    Physics-Electrostatics I-70713.png

  • Physics-Electrostatics I-70714.png

  • Physics-Electrostatics I-70715.png
In nature, the electric charge of any system is always equal to
  • Half integral multiple of the least amount of charge
  • Zero
  • Square of the least amount of charge
  • Integral multiple of the least amount of charge
Two small spheres each having the charge +Q are suspended by insulating threads of length L from a hook. This arrangement is taken in space where there is no gravitational effect, then the angle between the two suspensions and the tension in each will be

  • Physics-Electrostatics I-70718.png
  • 2)
    Physics-Electrostatics I-70719.png

  • Physics-Electrostatics I-70720.png

  • Physics-Electrostatics I-70721.png

Physics-Electrostatics I-70723.png

  • Physics-Electrostatics I-70724.png
  • 2)
    Physics-Electrostatics I-70725.png

  • Physics-Electrostatics I-70726.png

  • Physics-Electrostatics I-70727.png
A solid spherical conductor of radius R has a spherical cavity of radius a(a < R) at its centre. A charge +Q is kept at the center. The charge at the inner surface, outer and at a position r (a < r < R) are respectively
  • +Q, – Q, 0
  • –Q, + Q, 0
  • o, –Q, 0
  • +Q, 0, 0
There are two metallic spheres of same radii but one is solid and the other is hollow, then
  • Solid sphere can be given more charge
  • Hollow sphere can be given more charge
  • They can be charged equally (maximum)
  • None of the above

Physics-Electrostatics I-70730.png
  • 1/2
  • 2

  • Physics-Electrostatics I-70731.png

  • Physics-Electrostatics I-70732.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

Physics-Electrostatics I-70735.png
  • 18 N
  • 1.8 N
  • 0.18 N
  • None of these

Physics-Electrostatics I-70825.png
  • Is zero
  • Depends upon E

  • Physics-Electrostatics I-70826.png
  • Depends upon the atomic number of the conducting element
A force F acts between sodium and chlorine ions of salt (sodium chloride) when put 1 cm apart in air. The permittivity of air and dielectric constant of water are ɛ0 and K respectively. When a piece of salt is put in water electrical force acting between sodium and chlorine ions 1 cm apart is

  • Physics-Electrostatics I-70740.png
  • 2)
    Physics-Electrostatics I-70741.png

  • Physics-Electrostatics I-70742.png

  • Physics-Electrostatics I-70743.png
Two identical charges repel each other with a force equal to 10 mg wt when they are 0.6 m apart in air. (g = 10 ms–2). The value of each charge is
  • 2 mC
  • 2 nC
  • 2 × 10–7C
  • 2µC
The value of electric permittivity of free space is
  • 9 × 109NC2/ m2
  • 8.85 × 10–12Nm2/ C2 sec
  • 8.85 × 10–12C2/ Nm2
  • 9 × 109C2/ Nm2
Two similar spheres having +q and –q charge are kept at a certain distance. F force acts between the two. If in the middle of two spheres, another similar sphere having +q charge is kept, then it experience a force in magnitude and direction as
  • Zero having no direction
  • 8F towards +q charge
  • 8F towards –q charge
  • 4F towards +q charge
A charge Q is divided into two parts of q and Q – q. If the coulomb repulsion between them when they are separated is to be maximum, the ratio of Q/q should be
  • 2
  • 1/2
  • 4
  • 1/4
Number of electrons in one coulomb of charge will be
  • 5.46 × 1029
  • 6.25 × 1018
  • 1.6 × 10+19
  • 9 × 1011
When air is replaced by a dielectric medium of constant k, the maximum force of attraction between two charges separated by a distance
  • Decreases k times
  • Remains unchanged
  • Increases k times
  • Increases k–1 times
A glass rod rubbed with silk is used to charge a gold leaf electroscope and the leaves are observed to diverge. The electroscope thus charged is exposed to X-rays for a short period. Then
  • The divergence of leaves will not be affected
  • The leaves will diverge further
  • The leaves will collapse
  • The leaves will melt
The force between two charges 0.06m apart is 5N. 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
0:0:1


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