Consider two uncharged capacitors of equal capacitance 200 ~pF$200 \mathrm{~pF}$. One of them is charged by a 100 ~V$100 \mathrm{~V}$ supply and disconnected. Now this capacitor is connected to the uncharged capacitor. The amount of electrostatic energy lost in the process is:
When a charged capacitor is connected to an uncharged capacitor, charge redistributes until both reach a common potential, resulting in a loss of electrostatic energy (dissipated as heat/electromagnetic radiation).
Given:
C₁ = 200 ~pF = 200 × 10⁻¹² ~F$C_1 = 200 \mathrm{~pF} = 200 \times 10^{-12} \mathrm{~F}$C₂ = 200 ~pF = 200 × 10⁻¹² ~F$C_2 = 200 \mathrm{~pF} = 200 \times 10^{-12} \mathrm{~F}$V₁ = 100 ~V$V_1 = 100 \mathrm{~V}$V₂ = 0 ~V$V_2 = 0 \mathrm{~V}$ (since it is uncharged)
When a capacitor C$C$ charged to V$V$ is connected across an identical uncharged capacitor C$C$, exactly half of the initial stored energy is lost in redistribution.
Chapter Mix
Class 12 Physics: Electrostatic Potential and Capacitance
Keywords:#amount of electrostatic energy lost#NEET 2026 Code 12 Q31#Electrostatic Potential and Capacitance NEET 2026#Energy Stored in a Capacitor NEET 2026
More Electrostatic Potential and Capacitance Previous-Year Questions
Q15neet_2026_03_may_morningCombination of Capacitors
Five capacitors of capacitances C₁ = C₂ = C₃ = C₄ = 10 ~μ F$C_1 = C_2 = C_3 = C_4 = 10 \mathrm{~\mu F}$ and C₅ = 2.5 ~μ F$C_5 = 2.5 \mathrm{~\mu F}$ are connected as shown, along with a battery of 50 ~V$50 \mathrm{~V}$.
Circuit containing series and parallel combination of C1, C2, C3, C4 and C5 with 50V battery.
The equivalent capacitance and the charges on each capacitor respectively are:
A.5 ~μ F, 125 ~μ C on all capacitors$5 \mathrm{~\mu F}, 125 \mathrm{~\mu C} \text{ on all capacitors}$
B.5 ~μ F, 250 ~μ C on all capacitors$5 \mathrm{~\mu F}, 250 \mathrm{~\mu C} \text{ on all capacitors}$
C.4 ~μ F, 250 ~μ C on C₁ to C₄ and 125 ~μ C on C₅$4 \mathrm{~\mu F}, 250 \mathrm{~\mu C} \text{ on } C_1 \text{ to } C_4 \text{ and } 125 \mathrm{~\mu C} \text{ on } C_5$
D.5 ~μ F, 125 ~μ C on C₁ to C₄ and 25 ~μ C on C₅$5 \mathrm{~\mu F}, 125 \mathrm{~\mu C} \text{ on } C_1 \text{ to } C_4 \text{ and } 25 \mathrm{~\mu C} \text{ on } C_5$
The schematic Circuit containing series and parallel combination of C1, C2, C3, C4 and C5 with 50V battery. shows C₁, C₂, C₃, C₄$C_1, C_2, C_3, C_4$ are in series with each other. This entire series branch is in parallel with C₅$C_5$.
Equivalent capacitance of the series branch (C₁$C_1$ to C₄$C_4$):
Since CS$C_S$ and C₅$C_5$ have identical capacitance (2.5 ~μ F$2.5 \mathrm{~\mu F}$) and are in parallel, they draw identical charge. Thus, every capacitor in the array ends up with 125 ~μ C$125 \mathrm{~\mu C}$.
Chapter Mix
Class 12 Physics: Electrostatic Potential and Capacitance
Q41neet_2026_03_may_morningElectrostatics of Conductors
Which of the following statements are correct?
A. Inside a conductor, the electrostatic field is zero.
B. Electric field at the surface of a charged conductor does not depend on its surface charge density.
C. The interior of a charged conductor can have no excess charge in the static situation.
D. At the surface of a charged conductor, the electrostatic field must be normal to the surface at every point.
E. The electrostatic potential is zero everywhere inside a charged conductor.
Choose the correct answer from the options given below:
A.C, D and E only$\text{C, D and E only}$
B.A, B and D only$\text{A, B and D only}$
C.A, C and D only$\text{A, C and D only}$
D.A, C and E only$\text{A, C and E only}$
Solution
Core Logic
Evaluate each statement against the rules of electrostatics for conductors:
A. True. In electrostatic equilibrium, the electric field inside a solid or hollow conductor is precisely zero.
B. False. The electric field immediately outside the surface of a conductor is E = (σ)/(ε₀)$E = \frac{\sigma}{\varepsilon_0}$. It directly depends on the local surface charge density (σ$\sigma$).
C. True. Due to Gauss's Law (E = 0$E = 0$ inside), any excess charge must reside exclusively on the outer surface.
D. True. If the field had a tangential component, charges would flow along the surface, violating the static assumption. Thus, E$E$ must be strictly perpendicular (normal).
E. False. Since E = 0$E = 0$ inside, the potential (V$V$) must be constant, but not necessarily zero. It is equal to the potential at the surface.
Step 1: Final Conclusion
Only statements A, C, and D are correct.
Pattern Recognition
Watch for the "potential is zero" trap (Statement E). Potential is constant inside a conductor, but it only equals zero if the conductor is grounded.
Chapter Mix
Class 12 Physics: Electrostatic Potential and Capacitance
More Electrostatic Potential and Capacitance Questions — neet_2026_03_may_morning
Practice past-year questions one chapter at a time. Pick an exam → subject → chapter and get every PYQ for that topic — pulled together from all past papers — with the chapter's key formulas alongside.
