JEE Questions for Physics Electrostatics I Quiz 23 - MCQExams.com

If a slab of insulating material 4 × 10–3m thick is introduced between the plates of a parallel plate capacitor, the separation between plates has to be increased by 3.5 × 10–3m to restore the capacity to original value. The dielectric constant of the material will be
  • 6
  • 8
  • 10
  • 12
When a dielectric material is introduced between the plates of a charged condenser then electric field between the plates
  • Decreases
  • Increases
  • Remain constant
  • First (b) then (a)
A 40µF capacitor in a defibrillator is charge to 3000.V The energy stored in the capacitor is sent through the patient during a pulse of duration 2 ms. The power delivered to the patient is
  • 45 kW
  • 90 kW
  • 180 kW
  • 360 kW
Two metallic spheres of radii 1 cm and 2 cm are given charges 10–2 C and 5 × 10–2 C respectively. If they are connected by a conducting wire, the final charged onthe smaller sphere is
  • 1 × 10–2 C
  • 4 × 10–2 C
  • 3 × 10–2 C
  • 2 × 10–2 C
The capacity of a parallel plate condenser is 15µF, when the distance between its plates is 6 cm. If the distance between the plates is reduced to 2 cm, then the capacity of this parallel plate condenser will be
  • 15µF
  • 30µF
  • 45µF
  • 60µF
When we touch the terminals of a high voltage capacitor, even after a high voltage been cut off, then the capacitor has a tendency to
  • Restore energy
  • Discharge energy
  • Affect dangerously
  • Both (b) and (c)
What is the value of capacitance if the thin metallic plate is introduced between two parallel plated of area A and separated at distance d?

  • Physics-Electrostatics I-72540.png
  • 2)
    Physics-Electrostatics I-72541.png

  • Physics-Electrostatics I-72542.png

  • Physics-Electrostatics I-72543.png
The capacity of a parallel plate capacitor with no dielectric substance but with a separation of 0.4 cm is 2µF. The separation is reduced to half and it is filled with a dielectric substance of value 2.8. The final capacity of the capacitor is
  • 11.2µF
  • 15.6µF
  • 19.2µF
  • 22.4µF
Two insulated metallic spheres of 3µF and 5µF capacitances are charged to 300V and 500V respectively. The energy loss, when they connected by a wire is
  • 0.012 J
  • 0.0218 J
  • 0.0375 J
  • 3.75 J
A body of capacity 4µF is charged to 80 V and another body of capacity 6µF is charged to 30 V. When they are connected the energy lost by 4µF capacitor is
  • 7.8 mJ
  • 4.6 mJ
  • 3.2 mJ
  • 2.5 mJ
Two spherical conductors A and B of radius a andb (b >a) are placed in air concentrically B isgiven charge +Q coulomb and A is grounded. The equivalent capacitance of these is

  • Physics-Electrostatics I-72547.png
  • 2)
    Physics-Electrostatics I-72548.png

  • Physics-Electrostatics I-72549.png

  • Physics-Electrostatics I-72550.png
A charge of 40µC is given to a capacitor having capacitance (C = 10µF) The stored energy is ergs is
  • 8 × 10–6
  • 800
  • 80
  • 8000
The electric field between the plates of a parallel plate capacitor when connected to a certain battery is E0. If the space between the plates of the capacitor is filled by introducing a material of dielectric constant K without disturbing the battery connections, the field between the plates shall be
  • KE0
  • E0

  • Physics-Electrostatics I-72552.png
  • None of the above
If the distance between parallel plates of a capacitor is halved and dielectric constant is doubled then the capacitance
  • Decreases two times
  • Increases two times
  • Increases four times
  • Remains the same
Putting a dielectric substance between two plates of condenser, capacity, potential and potential energy respectively
  • Increase, decrease, decrease
  • Decrease, increase, increase
  • Increase, increase, increase
  • Decrease, decrease, decrease
A conducting sphere of radius 10 cm is charged 10µC. Another uncharged sphere of radius 20 cm is allowed to touch it for some time. After that if the sphere are separated, then surface density of charges, on thespheres will be in the ration of
  • 1 : 4
  • 1 : 3
  • 2 : 1
  • 1 : 1
Capacitance (in F) of a spherical conductor with radius1 m is
  • 1.1 × 10–10
  • 10–6
  • 9 × 10–9
  • 10–3
On increasing the plate separation of a charged condenser, the energy
  • Increases
  • Decreases
  • Remains unchanged
  • Becomes zero
The energy required to charge a capacitor of 5µF by connecting a d. c. source of 20 kV is
  • 10 kJ
  • 5 kJ
  • 2 kJ
  • 1 kJ
The capacitance of a parallel plate capacitor is 12 µF. If the distance between the plates is doubled and area is halved, then new capacitance will be
  • 8µF
  • 6µF
  • 4µF
  • 3µF
A capacitor of capacitance 611F is charged upto 100 volt. The energy stored in the capacitor is
  • 0.6 Joule
  • 0.06 Joule
  • 0.03 Joule
  • 0.3 Joule
A parallel plate capacitor of capacity C0 is charged to a potential V0
(i) The energy stored in the capacitor when the battery is disconnected and the separation is doubled E1
(ii) The energy stored in the capacitor when the charging battery is kept connected and the separation between the capacitor plates is doubled is E2. Then E1/E2 value is
  • 4
  • 3/2
  • 2
  • 1/2
As in figure shown, if a capacitor C is charged by connecting it with resistance R, then energy is givenby the battery will be
Physics-Electrostatics I-72562.png

  • Physics-Electrostatics I-72563.png
  • 2)
    Physics-Electrostatics I-72564.png

  • Physics-Electrostatics I-72565.png
  • Zero
When a lamp is connected in series with capacitor, then
  • Lamp will not glow
  • Lamp will burst out
  • Lamp will glow normally
  • None of the above
If a dielectric substance is introduced between the plates of a charged air-gap capacitor. The energy of the capacitor will
  • Increase
  • Decrease
  • Remain unchanged
  • First decrease and then increase
Which is known as capacitive time constant?
  • R/L
  • R/C
  • R/LC

  • Physics-Electrostatics I-72567.png
The net charge on capacitor is
  • 2q
  • q/2
  • 0
  • ∞
A capacitor of capacitance C is charged to a potential V. The flux of the electric field through a closed surface enclosing the capacitor is

  • Physics-Electrostatics I-72568.png
  • 2)
    Physics-Electrostatics I-72569.png

  • Physics-Electrostatics I-72570.png
  • Zero
If the charge on a capacitor is doubled, the value of its capacitance C will be
  • Doubled
  • Halved
  • Remain the same
  • None of these
A parallel plate capacitor of a capacitance of 1 faradwould have the plate area of about
  • 100 m2
  • 1 km2
  • 100 km2
  • 1000 km2
A parallel plate condenser has a uniform electric field E(V/m) in the space between the plates. If the distance between the plates is d(m) and area of each plates is A(m2) the energy (joules) stored in the condenser is

  • Physics-Electrostatics I-72571.png
  • 2)
    Physics-Electrostatics I-72572.png

  • Physics-Electrostatics I-72573.png

  • Physics-Electrostatics I-72574.png
The condensers of capacity C1 and C2 and connected in parallel, then the equivalent capacitance is

  • Physics-Electrostatics I-72575.png
  • 2)
    Physics-Electrostatics I-72576.png

  • Physics-Electrostatics I-72577.png

  • Physics-Electrostatics I-72578.png
A parallel plate capacitor is made by stacking n equally spaced plates connected alternately. If the capacitance between any two plates C then the resultant capacitance is
  • C
  • nC
  • (n – 1)C
  • (n + 1)C
Four plates of equal area Aare separated by equal distances d and are arranged as shown in the figure. The equivalent capacity is
Physics-Electrostatics I-72580.png

  • Physics-Electrostatics I-72581.png
  • 2)
    Physics-Electrostatics I-72582.png

  • Physics-Electrostatics I-72583.png

  • Physics-Electrostatics I-72584.png
A parallel plate capacitor with air as medium between the plates has a capacitance of 10 µF. The area of capacitor is divided into two equal halves and filled with two media as shown in the figure having dielectric constant k1 = 2 and k2 = 4. The capacitance of the system will now be
Physics-Electrostatics I-72591.png
  • 10 µF
  • 20 µF
  • 30µF
  • 40µF
Three capacitors are connected to D.C. source of 100 volts shown in the adjoining figure. If the charge accumulated on plates of C1, C2 and C3 are qa, qb, qc,qd, qe and qf respectively, then
Physics-Electrostatics I-72593.png

  • Physics-Electrostatics I-72594.png
  • 2)
    Physics-Electrostatics I-72595.png

  • Physics-Electrostatics I-72596.png

  • Physics-Electrostatics I-72597.png
Five capacitors of 10 µF capacity each are connected at a d.c.potential of 100 volts as shown in the adjoining figure. The equivalent capacitance between the points A and B will be equal to
Physics-Electrostatics I-72598.png
  • 40µF
  • 20µF
  • 30µF
  • 10µF

Physics-Electrostatics I-72600.png
  • 1 : 15
  • 15 : 1
  • 1 : 1
  • 1 ; 3
Four condensers each of capacity 4 µF are connected as shown in figure. VP– VQ = 15 volts. The energy stored in the system is
Physics-Electrostatics I-72602.png
  • 2400 ergs
  • 1800 ergs
  • 3600 ergs
  • 5400 ergs
Two capacitors each of 1µF capacitance are connected in parallel and are then charged by 200 volts d. c. supply. The total energy of their charges (in joules) is
  • 0.01
  • 0.02
  • 0.04
  • 0.06
In an adjoining figure are shown three capacitors C1, C2 and C3 joined to a battery. The correct condition will be (Symbols have their usual meanings)
Physics-Electrostatics I-72605.png
  • Q1 = Q2 = Q3 and V1 = V2 = V3 = V
  • Q1 = Q2+ Q3 and V = V1+ V2+ V3
  • Q1 = Q2+ Q3 and V = V1 + V2
  • Q2 = Q3 and V2 = V3
Two condensers of capacity 0.3µF and0.6µF respectively are connected in series. The combination is connected across a potential of 6 volts. The ratio of energies stored by the condensers will be
  • 1 : 2
  • 2 : 1
  • 1 : 4
  • 4 : 1
Three capacitances of capacity 10µF, 5µF and 5µF are connected in parallel. The total capacity will be
  • 10µF
  • 5µF
  • 20µF
  • None of these
Three capacitors of capacity C1, C2, C3 are connected in series. Their total capacity will be

  • Physics-Electrostatics I-72609.png
  • 2)
    Physics-Electrostatics I-72610.png

  • Physics-Electrostatics I-72611.png
  • None of the above
Five capacitors, each of capacitance value C are connected as shown in the figure. The ratio of capacitance between P and R and the capacitancebetween P and Q, is
Physics-Electrostatics I-72613.png
  • 3 : 1
  • 5 : 2
  • 2 : 3
  • 1 : 1
A capacitor of capacity C1 is charged to the potential of V0. On disconnecting with the battery, it is connected with a capacitor of capacity C2 as shown in the adjoining figure. The ratio of energies before and after the connection of switch S will be
Physics-Electrostatics I-72615.png
  • (C1 + C/ C1
  • C1 / (C1 + C2)
  • C1C2
  • C1 / C2
The capacities of two conductors are C1 and C2 and their respective potentials are V1 and V2. If they are connected by a thin wire, given by

  • Physics-Electrostatics I-72617.png
  • 2)
    Physics-Electrostatics I-72618.png

  • Physics-Electrostatics I-72619.png

  • Physics-Electrostatics I-72620.png
A parallel plate condenser is filled with two dielectric as shown. Area of each plate is A metre2 and the separation is t metre. The dielectric constants are k1 and k2 respectively. Its capacitance in farad will be
Physics-Electrostatics I-72621.png

  • Physics-Electrostatics I-72622.png
  • 2)
    Physics-Electrostatics I-72623.png

  • Physics-Electrostatics I-72624.png

  • Physics-Electrostatics I-72625.png
Three condensers each of capacitance 2F are put in series. The resultant capacitance is
  • 6F
  • 2)
    Physics-Electrostatics I-72627.png

  • Physics-Electrostatics I-72628.png
  • 5F
Two condensers of capacities 1 µF and 2 µF are connected in series and the system is charged to 120 volts. Then the P.D. on 1 µF capacitor (in volts) willbe
  • 40
  • 60
  • 80
  • 120
0:0:1


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