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Charged capacitor joined to another capacitor (uncharged or at a different potential): charges, common potential and energy lost

This type of question, asked 12 times: 26 Jun 2022, 27 Jun 2022, 28 Jun 2022, 30 Jan 2023, 8 Apr 2023, 11 Apr 2023, 30 Jan 2024, 1 Feb 2024, 29 Jan 2025, 3 Apr 2025, 22 Jan 2026 S2, 6 Apr 2026 S2. All 12 questions below, oldest first.

Try each one first, then open its answer.

  1. Question 1

    26 Jun 2022

    10
    Two capacitors having capacitance C1C_{1} and C2C_{2} respectively are connected as shown in figure. Initially, capacitor C1C_{1} is charged to a potential difference VV volt by a battery. The battery is then removed and the charged capacitor C1C_{1} is now connected to uncharged capacitor C2C_{2} by closing the switch S. The amount of charge on the capacitor C2C_{2}, after equilibrium is:

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  2. Question 2

    27 Jun 2022

    27
    A capacitor of capacitance 50pF50pF is charged by 100 VV source. It is then connected to another uncharged identical capacitor. Electrostatic energy loss in the process is ____\_\_\_\_ nJ.

  3. Question 3

    28 Jun 2022

    116
    A capacitor C1C_{1} of capacitance 5μF5\mu F is charged to a potential of 30 V30\text{ }V using a battery. The battery is then removed and the charged capacitor is connected to an uncharged capacitor C2C_{2} of capacitance 10μF10\mu F as shown in figure. When the switch is closed charge flows between the capacitors. At equilibrium, the charge on the capacitor C2C_{2} is μC\mu C.

  4. Question 4

    30 Jan 2023

    29
    A capacitor of capacitance 900μF900\mu F is charged by a 100 V100\text{ }V battery. The capacitor is disconnected from the battery and connected to another uncharged identical capacitor such that one plate of uncharged capacitor connected to positive plate and another plate of uncharged capacitor connected to negative plate of the charged capacitor. The loss of energy in this process is measured as x×10−2 Jx \times10^{- 2}\text{ }J. The value of xx is

  5. Question 5

    8 Apr 2023

    118
    A 600pF600pF capacitor is charged by 200 V200\text{ }V supply. It is then disconnected from the supply and is connected to another uncharged 600pF600pF capacitor. Electrostatic energy lost in the process is ___μJ\_\_\_\mu J.

  6. Question 6

    11 Apr 2023

    6
    A parallel plate capacitor of capacitance 2 F2\text{ }F is charged to a potential V. The energy stored in the capacitor is E1E_{1}. The capacitor is now connected to another uncharged identical capacitor in parallel combination. The energy stored in the combination is E2E_{2}. The ratio E2/E1E_{2}/E_{1} is:

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  7. Question 7

    30 Jan 2024

    27
    A capacitor of capacitance CC and potential VV has energy E. It is connected to another capacitor of capacitance 2C2C and potential 2 V2\text{ }V. Then the loss of energy is x3E\frac{x}{3}E, where xx is _______ .

  8. Question 8

    1 Feb 2024

    5
    Two identical capacitors have same capacitance CC. One of them is charged to the potential VV and other to the potential 2 V2\text{ }V. The negative ends of both are connected together. When the positive ends are also joined together, the decrease in energy of the combined system is:

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  9. Question 9

    29 Jan 2025

    89
    A capacitor, C1=6μ FC_{1}= 6\mu\text{ }F is charged to a potential difference of V0=5 VV_{0}= 5\text{ }V using a 5 V battery. The battery is removed and another capacitor, C2=12C_{2}= 12 μF\mu F is inserted in place of the battery. When the switch ' S ' is closed, the charge flows between the capacitors for some time until equilibrium condition is reached. What are the charges (q1\left( q_{1} \right. and q2q_{2} ) on the capacitors C1C_{1} and C2C_{2} when equilibrium condition is reached.

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  10. Question 10

    3 Apr 2025

    83
    Using a battery, a 100 pF capacitor is charged to 60 V and then the battery is removed. After that, a second uncharged capacitor is connected to the first capacitor in parallel. If the final voltage across the second capacitor is 20 V , its capacitance is : (in pF)

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  11. Question 11

    22 Jan 2026 S2

    23
    A capacitor PP with capacitance 10×10−6 F10 \times 10^{- 6}\text{ }F is fully charged with a potential difference of 6.0 V and disconnected from the battery. The charged capacitor PP is connected across another capacitor QQ with capacitance 20×10−6 F20 \times 10^{- 6}\text{ }F. The charge on capacitor QQ when equilibrium is established will be α×10−5C\alpha \times 10^{- 5}C (assume capacitor QQ does not have any charge initially), the value of α\alpha is ____\_\_\_\_.

  12. Question 12

    6 Apr 2026 S2

    15
    A sphere of capacitance 100 pF is charged to a potential of 100 V . Another identical uncharged metal sphere is brought in contact with the charged sphere, then the change in the total energy stored on these spheres, when they touch is α×10−7 J\alpha \times10^{- 7}\text{ }J. The value of α\alpha is ____\_\_\_\_ . (combined capacitance of spheres is 200 pF ).

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