JEE Questions for Physics Electrostatics I Quiz 12 - MCQExams.com

A capacitor of capacity C is connected with a battery of potential V in parallel. The distance between its plates is reduced to half at once, assuming that the charge remains the same. Then to charge the capacitance upto the potential V again, the energy given by the battery will be

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  • 2)
    Physics-Electrostatics I-71250.png

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  • Physics-Electrostatics I-71252.png
A 6 µF capacitor is charge from 10 volts to 20 volts. Increase in energy will be
  • 18 × 10–4 J
  • 9 × 10–4 J
  • 4.5 × 10–4 J
  • 9 × 10–6 J
As shown in the figure, a very thin sheet of aluminum is placed in between the plates of the condenser. Then the capacity
Physics-Electrostatics I-71255.png
  • Will increase
  • Will decrease
  • Remains unchanged
  • May increase or decrease
An air capacitor is charged with an amount of charge q and dipped into an oil tank. If the oil is pumped out, the electric field between the plates of capacitor will
  • Increase
  • Decrease
  • Remain the same
  • Become zero
The outer sphere of a spherical air capacitor is earthed. For increasing its capacitance
  • Vaccum is created between two spheres
  • Dielectric material is filled between the two spheres
  • The space between two spheres is increased
  • The earthing of the outer sphere is removed
The plates of parallel plate capacitor are charged upto 100V. A2 mm thick plate is inserted between the plates. Then to maintain the same potential difference, the distance between the plates is increased by 1.6mm. The dielectric constant of the plate is
  • 5
  • 4
  • 1.25
  • 2.5
Force acting upon a charged particle kept between the plates of a charged condenser is F. If one plate of the condenser is removed, then the force acting on the same particle will become
  • 0
  • F/2
  • F
  • 2F
Two metallic charged spheres whose radii are 20 cm and 10 cm respectively, have each 150 micro-coulomb positive charge. The common potential after they are connected by a conducting wire is
  • 9 × 106 volts
  • 4.5 × 106 volts
  • 1.8 × 107 volts
  • 13.5 × 106 volts
A parallel plate air capacitor has a capacitance C. When it is half filled with a dielectric of dielectric constant 5,the percentage increase in the capacitance will be
Physics-Electrostatics I-71261.png
  • 400%
  • 66.6%
  • 33.3%
  • 200%
A frictionless dielectric plate S is kept on a frictionless table T. A charged parallel plate capacitance C (of which the plates are frictionless) is kept near it. The plate S is in between the plates. When the plate S is left between the plates
Physics-Electrostatics I-71263.png
  • It will remain stationary on the table
  • It is pulled by the capacitor and will pass on the other end
  • It is pulled between the plates and will remain there
  • All of the above statements are false
A capacitor with air as the dielectric is charged to a potential of 100 volts. If the space between the plate is now filled with a dielectric of dielectric constant 10, the potential difference between the plates will be
  • 1000 volts
  • 100 volts
  • 10 volts
  • Zero
The distance between the circular plates of a parallel plate condenser 40mm in diameter, in order to have same capacity as a sphere of radius 1 metre is
  • 0.01 mm
  • 0.1 mm
  • 1.0 mm
  • 10 mm
When a slab of dielectric material is introduced between the parallel plates of a capacitor which remains connected to a battery, then charge on plates relative to earlier charge
  • Is less
  • Is same
  • Is more
  • May be less or more depending on the nature of the material introduced
The capacitance of a parallel plate condenser does not depend on
  • Area of the plates
  • Medium between the plates
  • Distance between the plates
  • Metal of the plates
Between the plates of a parallel plate condenser there is 1mm thick paper of dielectric constant 4. It is charged at 100 volt. The electric field in volt/metre between the plates of the capacitor is
  • 100
  • 100000
  • 25000
  • 4000000
The electric field between the two spheres of a charged spherical condenser
  • Is zero
  • Is constant
  • Increases with distance from the centre
  • Decreases with distance from the centre
The distance between the plates of a parallel plates capacitor is d. A metal plate of thickness d / 2 is placed between the plates. The capacitance would then be
  • Unchanged
  • Halved
  • Zero
  • Doubled
An uncharged capacitor is connected to a battery. On charging the capacitor
  • All the energy supplied is stored in the capacitor
  • Half the energy supplied is stored in the capacitor
  • The energy stored depends upon the capacity of the capacitor only
  • The energy stored depends upon the time for which the capacitor is charged
A capacitor is kept connected to the battery and a dielectric slab is inserted between the plates. During this process
  • No work is done
  • Work is done at the cost of the energy already stored in the capacitor before the slab is inserted
  • Work is done at the cost of the battery
  • Work is done at the cost of both the capacitor and the battery
The capacitance of an air capacitor is 15µF the separation between the parallel plate is 6 mm. A copper plate of 3 mm thickness is introduced symmetrically between the plates. The capacitance now becomes
  • 5µF
  • 7.5µF
  • 22.5 µF
  • 30µF
An air capacitor is connected to a battery. The effect of filling the space between the plates with a dielectric is to increase
  • The charge and the potential difference
  • The potential difference and the electric field
  • The electric field and the capacitance
  • The charge and the capacitance
A light bulb, a capacitor and a battery are connected together as shown here, with switch S initially open, When the switch S is closed, which one of the following is true
Physics-Electrostatics I-71270.png
  • The bulb will light up for an instant when the capacitor starts charging
  • The bulb will light up when the capacitor is fully charged
  • The bulb will not light up at all
  • The bulb will light up and go off at regular intervals
A spherical condenser has inner and outer spheres of radii a and b respectively. The space between the two is filled with air. The difference between the capacities of two condensers formed when outer sphere is earthed and when inner sphere is earthed will be
  • Zero
  • 2)
    Physics-Electrostatics I-71272.png

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The expression for the capacity of the capacitor formed by compound dielectric placed between the plates of a parallel plate capacitor as shown in figure, will be (area of plate = A)
Physics-Electrostatics I-71275.png

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  • 2)
    Physics-Electrostatics I-71277.png

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The intensity of electric field at a point between the plates of a charged capacitor
  • Is directly proportional to the distance between the plates
  • Is inversely proportional to the distance between the plates
  • Is inversely proportional to the square of the distance between the plates
  • Does not depend upon the distance between the plates
The capacity of a condenser in which a dielectric of dielectric constant 5 has been used, is C. If the dielectric is replaced by another with dielectric constant 20, the capacity will become

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  • 4 C

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  • 2 C
A parallel plate condenser with a dielectric of dielectric constant K between the plates has a capacity C and is charged to a potential V volts. The dielectric slab is slowly removed from between the plates and then reinserted. The net work done by the system in this process is

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  • 2)
    Physics-Electrostatics I-71285.png

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  • Zero
A charge of 10–9C is placed on each of the 64 identical drops of radius 2 cm. They are then combined to form a bigger drop. Find its potential
  • 7.2 × 103 V
  • 7.2 × 102 V
  • 1.44 × 102 V
  • 1.44 × 103 V
To increase the charge on the plate of a capacitor means to
  • Decrease the potential difference between the plates
  • Decrease the capacitance of the capacitor
  • Increase the capacitance of the capacitor
  • Increase the potential difference between the plates
Two spherical conductors each of capacity C are charged to potentials V and –V. These are then connected by means of a fine wire. The loss of energy will be
  • Zero
  • 2)
    Physics-Electrostatics I-71288.png

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The area of the plates of a parallel plate condenser is A and the distance between the plates is 10mm. There are two dielectric sheets in it, one of dielectric constant 10 and thickness 6mm and the other of dielectric constant 5 and thickness 4mm. The capacity of the condenser is

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  • 2)
    Physics-Electrostatics I-71293.png

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An air capacitor of capacity C =10µF is connected to a constant voltage battery of 12V. Now the space between the plates is filled with a liquid of dielectric constant 5. The charge that flows now from battery to the capacitor is
  • 120µC
  • 699µC
  • 480µC
  • 24 µC
A parallel plate capacitor is first charged and then a dielectric slab is introduced between the plates. The quantity that remains unchanged is
  • Charge Q
  • Potential V
  • Capacity C
  • Energy U
The force between the plates of a parallel plate capacitor of capacitance C and distance of separation of the plates d with a potential difference V between the plates, is

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  • 2)
    Physics-Electrostatics I-71299.png

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Two metal spheres of capacitance C1 and C2 carry some charges. They are put in contact and then separated. The final charges Q1 and Q2 on them will satisfy

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  • 2)
    Physics-Electrostatics I-71303.png

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What is the area of the plates of a 3F parallel plate capacitor, if the separation between the plates is 5 mm
  • 1.694 × 109 m2
  • 4.529 × 109 m2
  • 9.281 × 109 m2
  • 12.981 × 109 m2
A parallel plate capacitor has circular plates of 0.08 m radius and 1.0 × 10–3 m separation. If a P.D. of 100 volt is applied, the charge will be
  • 1.8 × 10–10 C
  • 1.8 × 10–8 C
  • 1.8 × 10–20 C
  • None of these
The capacity of a parallel plate condenser is 10 µF without dielectric. Dielectric of constant 2 is used to fill half the distance between the plates, the new capacitance in µF is
  • 10
  • 20
  • 15
  • 13.33
A battery is used to charge a parallel plate capacitor till the potential difference between the plates becomes equal to the electromotive force of the battery. The ratio of the energy stored in the capacitor and the work done the battery will be
  • 1
  • 2
  • 1/4
  • 1/2
Two protons A and B are placed in space between plates of a parallel plate capacitor charged upto V volts (See fig.). Forces on protons are FA and FB, then
Physics-Electrostatics I-71310.png
  • FA > FB
  • FA < FB
  • FA = FB
  • Nothing can be said
A parallel plate capacitor has a plate separation of 0.01 mm and use a dielectric (whose dielectric strength is 19KV / mm) as an insulator. The maximum potential difference that can be applied to the terminals of the capacitor is
  • 190 V
  • 290 V
  • 95 V
  • 350 V
A variable condenser is permanently connected to a 100V battery. If the capacity is changed from 2 µF to 10 µF, then change in energy is equal to
  • 2 × 10–2 J
  • 2.5 × 10–2 J
  • 3.5 × 10–2 J
  • 4 × 10–2 J
A parallel plate capacitor having a plate separation of 2 mm is charged by connecting it to a 300V supply. The energy density is
  • 0.01J/m3
  • 0.1J /m3
  • 1. 0 J/m3
  • 10 J/m3
In a capacitor of capacitance 20µF, the distance between the plates is 2mm. If a dielectric slab of width 1mm and dielectric constant 2 is inserted between the plates, then the new capacitance is
  • 2 µF
  • 15.5 µF
  • 26.6 µF
  • 32 µF
Two conducting spheres of radii 5cm and 10cm are given a charge of 15µF each. After the two spheres are joined by a conducting wire, the charge on the smaller sphere is
  • 5µC
  • 10µC
  • 15µC
  • 20µC
In a parallel plate capacitor of capacitance C, a metal sheet is inserted between the plates, parallel to them. If the thickness of the sheet is half of the separation between the plates. The capacitance will be
  • C/2
  • 3C/4
  • 4C
  • 2C
While a capacitor remains connected to a battery and dielectric slab is applied between the plates, then
  • Potential difference between the plates is changed
  • Charge flows from the battery to the capacitor
  • Electric field between the plates increases
  • Energy store in the capacitor decreases
The capacity of the conductor does not depend upon
  • Charge
  • Voltage
  • Nature of the material
  • All of these
A solid conducting sphere of radius R1 is surrounded by another concentric hollow conducting sphere of radius R2. The capacitance of this assembly is proportional to

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  • 2)
    Physics-Electrostatics I-71319.png

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The energy stored in a condenser is in the form of
  • Kinetic energy
  • Electrostatic potential energy
  • Elastic energy
  • Magnetic energy
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