JEE Questions for Physics Electrostatics I Quiz 15 - MCQExams.com

In the given figure two tiny conducting balls of identical mass m and identical charge q hang from non-conducting threads of equal length L. Assume that θ is so small that tan θ ≈ sin θ , then for equilibrium x is equal to
Physics-Electrostatics I-71565.png

  • Physics-Electrostatics I-71566.png
  • 2)
    Physics-Electrostatics I-71567.png

  • Physics-Electrostatics I-71568.png

  • Physics-Electrostatics I-71569.png
Consider two points 1 and 2 in a region outside a charged sphere. Two points are not very far away from the sphere. If E and V represent the electric field vector and the electric potential, which of the following is not possible

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  • 2)
    Physics-Electrostatics I-71572.png

  • Physics-Electrostatics I-71573.png

  • Physics-Electrostatics I-71574.png
Three positive charges of equal value q are placed at the vertices of an equilateral triangle. The resulting lines of force should be sketched as in

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    Physics-Electrostatics I-71576.png

  • Physics-Electrostatics I-71577.png

  • Physics-Electrostatics I-71578.png
A uniform electric field pointing in positive x-direction exists in a region. Let A be the origin, B be the point on the x-axis at x = + 1 cm and C be the point on the y-axis at y = + 1 cm. Then, the potentials at the points A, B and C satisfy
  • VA < VB
  • VA > VB
  • VA < VC
  • VA > VC
The electric potential at a point (x, y) in the x-y plane is given by V = – kxy. The field intensity at a distance r from the origin varies as
  • r2
  • r

  • Physics-Electrostatics I-71580.png

  • Physics-Electrostatics I-71581.png
Two equal charges are separated by a distance d. A third charge placed on a perpendicular bisector at x distance will experience maximum coulomb force when

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    Physics-Electrostatics I-71584.png

  • Physics-Electrostatics I-71585.png

  • Physics-Electrostatics I-71586.png
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 of Q, when it is displaced by a small distance x along the x-axis, is approximately proportional to
  • x
  • x2
  • x3
  • 1/x
An elementary particle mass m and charge +e is projected with velocity v at a much more massive particle of charge Ze, where Z > 0. What is the closest possible approach of the incident particle?

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    Physics-Electrostatics I-71590.png

  • Physics-Electrostatics I-71591.png

  • Physics-Electrostatics I-71592.png
An electric dipole is situated in an electric field of uniform intensity E whose dipole moment is p and moment of inertia is I. If the dipole is displaced slightly from the equilibrium position, then the angular frequency of its oscillations is

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    Physics-Electrostatics I-71595.png

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  • Physics-Electrostatics I-71597.png
A metallic shell has a point charge ‘q’ kept inside its cavity. Which one of the following diagrams correctly represents the electric lines of forces?

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    Physics-Electrostatics I-71600.png

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  • Physics-Electrostatics I-71602.png
A small sphere carrying a charge \'q\' is hanging in between two parallel plates by a string of length L. Time period of pendulum is T0. When parallel plates are charged, the time period changes to T. The ratio T / T0 is equal to
Physics-Electrostatics I-71603.png

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    Physics-Electrostatics I-71605.png

  • Physics-Electrostatics I-71606.png
  • None of these
Three charges –q1, + q2 and –q3 are placed as shown in the figure. The x-component of the force on –q1 is proportional to
Physics-Electrostatics I-71608.png

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    Physics-Electrostatics I-71610.png

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  • Physics-Electrostatics I-71612.png
A solid conducting sphere having a charge Q is surrounded by an uncharged concentric 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 –3Q, the new potential difference between the same two surfaces is
  • V
  • 2V
  • 4V
  • –2V
Two point charges +q and –q are held fixed at (– d,and (d,respectively of a (X, Y) co-ordinate system. Then
  • E at all points on the Y-axis is along î
  • 2)
    Physics-Electrostatics I-71615.png
  • Dipole moment is 2qd directed along î
  • Work has to be done in bringing a test charge from infinity to the origin
A point charge of 40 stat coulomb is placed 2 cm in front of an earthed metallic plane plate of large size. Then the force attraction on the point charge is
  • 100 dynes
  • 160 dynes
  • 1600 dynes
  • 400 dynes
A piece of cloud having area 25 × 106 m2 and electric potential of 105 volts. If the height of cloud is 0.75 km, then energy of electric field between earth and cloud will be
  • 250 J
  • 750 J
  • 1225 J
  • 1475 J
Two point charges (+Q) and (–2Q) are fixed on the X-axis at positions a and 2a from origin respectively. At what positions on the axis, the resultant electric field is zero

  • Physics-Electrostatics I-71619.png
  • 2)
    Physics-Electrostatics I-71620.png

  • Physics-Electrostatics I-71621.png

  • Physics-Electrostatics I-71622.png
Six charges, three positive and three negative of equal magnitude are to be placed at the vertices of a regular hexagon such that the electric field at O is double the electric field when only one positive charge of same magnitude is placed at R. Which of the following arrangements of charges is possible for P, Q R, S, T and U respectively
Physics-Electrostatics I-71624.png
  • +, –, +, –, –, +
  • +, –, +, –, +, –
  • +, +, –, +, –, –
  • –, +, +, –, +, –
A charged particle q is shot towards another charged particle Q which is fixed, with a speed v. It approaches Q upto a closest distance r and then returns. If q were given a speed 2v, the closest distances of approach would be
Physics-Electrostatics I-71625.png
  • r
  • 2r
  • r/2
  • r/4
Four charges equal to –Q are placed at the four corners of a square and a charge q is at its centre. If the system is in equilibrium the value of q is

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    Physics-Electrostatics I-71628.png

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Capacitance of a capacitor made by a thin metal foil is 2 µF. If the foil is filled with paper of thickness 0.15 mm, dielectric constant of paper is 2.5 and width of paper is 400 mm, then length of foil will be
  • 0.34 m
  • 1.33 m
  • 13.4 m
  • 33.9 m
A particle of mass 2 × 10–5 kg and charge 4 × 10–3 C moves from rest in a uniform electric field of magnitude 5 V/m. Its kinetic energy after 10 seconds is
  • 2 × 103 J
  • 103 J
  • 2 × 10–3 J
  • 102 J
Five identical plates each of area A are joined as shown in the figure. The distance between the plates is d. The plates are connected to a potential difference of V volts. The charge on plates 1 and 4 will be
Physics-Electrostatics I-71634.png

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    Physics-Electrostatics I-71636.png

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Two condensers of capacities 2C and C are joined in parallel and charged upto potential V. The battery is removed and the condenser of capacity C is filled completely with a medium of dielectric constant K. The p.d. across the capacitors will now be

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  • 2)
    Physics-Electrostatics I-71641.png

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  • Physics-Electrostatics I-71643.png
In the figure below, what is the potential difference between the points A and B and between B and C respectively in steady state
Physics-Electrostatics I-71645.png
  • VAB = VBC = 100V
  • VAB = 75 V, VBC = 25 V
  • VAB = 25 V, VAB = 75 V
  • VAB = VBC = 50 V
Figure given below shows two identical parallel plate capacitors connected to a battery with switch S closed. The switch is now opened and the free space between the plate of capacitors is filled with a dielectric of dielectric constant 3. What will be the ratio of total electrostatic energy stored in both capacitors before and after the introduction of the dielectric?
Physics-Electrostatics I-71647.png
  • 3 : 1
  • 5 : 1
  • 3 : 5
  • 5 : 3
A parallel plate capacitor of capacitance C is connected to a battery and is charged to a potential difference V. Another capacitor of capacitance 2C is connected to another battery and is charged to potential difference 2V. The charging batteries are now disconnected and the capacitors are connected in parallel to each other in such a way that the positive terminal of one is connected to the negative terminal of the other. The final energy of the configuration is
  • Zero
  • 2)
    Physics-Electrostatics I-71649.png

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Condenser A has a capacity of 15 µF when it is filled with a medium of dielectric constant 15. Another condenser B has a capacity of 1 µF with air between the plates. Both are charged separately by a battery of 100 V. After charging, both are connected in parallel without the battery and the dielectric medium being removed. The common potential now is
  • 400 V
  • 800 V
  • 1200 V
  • 1600 V
Four metallic plates each with a surface area of one side A are placed at a distance d from each other. The plates are connected as shown in the circuit diagram. Then, the capacitance of the system between a and b is
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    Physics-Electrostatics I-71656.png

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In the given circuit if point C is connected to the earth and a potential of + 2000 V is given to the point A, the potential at B is
Physics-Electrostatics I-71660.png
  • 1500 V
  • 1000 V
  • 500 V
  • 400 V
A finite ladder is constructed by connecting several sections of 2 µF, 4 µF capacitor combinations as shown in the figure. It is terminated by a capacitor of capacitance C. What value should be chosen C such that the equivalent capacitance of the ladder between the points A and B becomes independent of the number of sections in between
Physics-Electrostatics I-71662.png
  • 4 µF
  • 2 µF
  • 18 µF
  • 6 µF
In an isolated parallel plate capacitor of capacitance C, the four surface have charges Q1, Q2, Q3 and Q4 as shown. The potential difference between the plates is
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    Physics-Electrostatics I-71665.png

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  • Physics-Electrostatics I-71667.png
For the circuit shown, which of the following statement is true?
Physics-Electrostatics I-71669.png
  • With S1 closed, V1 = 15 V, V2 = 20 V
  • With S3 closed, V1 = V2 = 25 V
  • With S1 and S2 closed, V1 = V2 = 0
  • With S1 and S3 closed, V1. = 30 V, V2 = 20 V
Consider the situation shown in the figure. 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-71671.png
  • Zero
  • q /2
  • q
  • 2q
A capacitor of capacitance C1 = 1 µF can with stand maximum voltage V1 = 6 kV (kilo-volt) and another capacitor of capacitance C2 = 3 µF can withstand maximum voltage V2 = 4 kV. When the two capacitors are connected in series, the combined system can withstand a maximum voltage of
  • 4 kV
  • 6 kV
  • 8 kV
  • 10 kV
In the given figure each plate of capacitance C has partial value of charge
Physics-Electrostatics I-71673.png
  • CE
  • 2)
    Physics-Electrostatics I-71674.png

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  • Physics-Electrostatics I-71676.png
The plates of a capacitor are charged to a potential difference of 320 volts and are then connected across a resistor. The potential difference across the capacitor decays exponentially with time. After 1 second the potential difference between the plates of the capacitor is 240 volts, then after 2 and 3 seconds the potential difference between the plates will be
  • 200 and 180 V
  • 180 and 135 V
  • 160 and 80 V
  • 140 and 20 V
The plates of a parallel plate condenser are pulled apart with a velocity v. If at any instant their mutual distance of separation is d, then the magnitude of the time of rate of change of capacity depends on d as follows
  • 1/d
  • 1/d2
  • d2
  • d
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

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    Physics-Electrostatics I-71681.png

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  • Physics-Electrostatics I-71683.png
A 4 µF capacitor, a resistance of 2.5 M Ω is in series with 12 V battery. Find the time after which the potential difference across the capacitor is 3 times the potential difference across the resistor. [Given In (=0.693]]
  • 13.86 s
  • 6.93 s
  • 7 s
  • 14 s
A parallel plate capacitor of area A, plate separation d and capacitance C is filled d with three different dielectric materials having dielectric constants k1, k2 and k3 as shown. If a single dielectric material is to be used to have the same capacitance C in this capacitor, then its dielectric constant k is given by
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    Physics-Electrostatics I-71688.png

  • Physics-Electrostatics I-71689.png

  • Physics-Electrostatics I-71690.png
In the figure a capacitor is filled with dielectrics. The resultant capacitance is
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  • 2)
    Physics-Electrostatics I-71694.png

  • Physics-Electrostatics I-71695.png
  • None of the above

Physics-Electrostatics I-71697.png
  • 18, 18/9, 4
  • 18, 4, 8/9
  • 4, 8/9, 18
  • 8/9, 18, 4

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    Physics-Electrostatics I-71701.png

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  • Physics-Electrostatics I-71703.png
Two equal negative charges –q are fixed at points (0, a) and (0, – a) on the Y-axis. A positive charge \'q\' is released from rest at the point (x << a) on the x-axis. What is the frequency of motion?

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  • 2)
    Physics-Electrostatics I-71706.png

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  • Physics-Electrostatics I-71708.png
A spherical portion has been removed from a solid sphere having a charge distributed uniformly in its volume in the figure. The electric field inside the emptied space is
Physics-Electrostatics I-71710.png
  • Zero everywhere
  • Non-zero and uniform
  • Non-uniform
  • Zero only at its centre
A circuit is connected as shown in the figure with the switch S open. When the switch is closed, the total amount of charge that flows from Y to X is
Physics-Electrostatics I-71712.png
  • 0 µC
  • 54 µC
  • 27 µC
  • 81 µC

Physics-Electrostatics I-71714.png
  • 3
  • 5
  • 2
  • Both (a) and (b)
A parallel plate capacitor C with plates of unit area and separation d is filled with a liquid of dielectric constant K = 2. The level of liquid is d/3 initially. Suppose, the liquid level decreases at a constant speed V, the time constant as a function of time t is
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    Physics-Electrostatics I-71718.png

  • Physics-Electrostatics I-71719.png

  • Physics-Electrostatics I-71720.png
A uniformly charged thin spherical shell of radius R carries uniform surface charge density of σ per unit area. It is made of two hemispherical shells, held together by pressing them with force F(see figure). F is proportional to
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  • 2)
    Physics-Electrostatics I-71724.png

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  • Physics-Electrostatics I-71726.png
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