JEE Main · Physics ↓ Falling

Electrostatic Potential and Capacitance appeared 13 times across 3 years — 1.5% of Physics. This question is from Energy Stored in a Capacitor.

Year 2026 2025 2024 Total
Questions 3 7 3 13

Two capacitors C₁ and C₂ are connected in parallel to a battery. Charge-time graph is shown below for the two capacitors. The energy stored with them are U₁ and U₂ , respectively. Which of the given statements is true?
Energy Stored in a Capacitor diagram for Q1 - JEE Main 2025 Morning
The graph shows the variation of charge with time for two different capacitors connected in parallel.

Solution & Explanation

Related Formula
V = same U = (1)/(2) CV² q = CV
Core Logic

Since both capacitors are connected in parallel across the same battery, their potential difference V is identical.

From the given charge-time graph, at any specific instant of time, the charge accumulated on the second capacitor is greater than that on the first:

q₂ > q₁

Using the relation q = CV, since V is identical, we get:

C₂ > C₁

Now, the electrostatic energy stored in a capacitor is given by:

U = (1)/(2) CV²

Since C₂ > C₁ and V is constant, the stored energy satisfies:

U₂ > U₁
Step 1: Final Conclusion

Thus, the correct relationships are C₂ > C₁ and U₂ > U₁.

Pattern Recognition

Sees parallel connection → Immediately lock potential difference V as constant. This simplifies q ∝ C and U ∝ C, creating a direct linear bridge from graph height to energy capacity.

Chapter Mix

Class 12 Physics: Electrostatic Potential and Capacitance

Reference Study Guides

More Electrostatic Potential and Capacitance Previous-Year Questions — Page 3

Q35 jee_main_2024_01_february_morning Capacitors and Capacitance
Two identical capacitors have same capacitance C. One of them is charged to the potential V and other to the potential 2V. 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:
  • A. (1)/(4) CV²
  • B. 2 CV²
  • C. (1)/(2) CV²
  • D. (3)/(4) CV²

Solution

Related Formula

Energy stored in a capacitor:

U = (1)/(2)CV²

Common potential after sharing charges:

VC = (q₁ + q₂)/(C₁ + C₂)

Loss of energy:

Δ U = (1)/(2) (C₁ C₂)/(C₁ + C₂) (V₁ - V₂)²
Core Logic

Initial energy of the individual systems:

Uᵢ = (1)/(2)CV² + (1)/(2)C(2V)² = (1)/(2)CV² + 2CV² = (5)/(2)CV²

Common potential VC when joined in parallel:

VC = (CV + C(2V))/(C + C) = (3CV)/(2C) = (3)/(2)V
Step 1: Calculate Final Energy and Loss

Final energy of the combined system:

Uf = (1)/(2)(2C)VC² = C ((3)/(2)V)² = (9)/(4)CV²

Decrease in energy (loss):

Δ U = Uᵢ - Uf = (5)/(2)CV² - (9)/(4)CV² = (1)/(4)CV²
Pattern Recognition

Direct Formula Shortcut:

Δ U = (1)/(2) (C · C)/(2C) (2V - V)² = (1)/(4)C(V)² = (1)/(4)CV²
Chapter Mix

Class 12 Physics: Electrostatic Potential and Capacitance

Q56 jee_main_2024_29_january_evening Capacitance and Resistor Networks at Steady State
In the given figure, the charge stored in 6 capacitor, when points A and B are joined by a connecting wire is ________ .
Capacitor-resistor bridge circuit for Q56 - JEE Main 2024 29 January Shift 2
The diagram displays a bridge-like network containing a 6 Ohm resistor, 3uF capacitor, 6uF capacitor, and 3 Ohm resistor powered by a 9V supply.
Numerical Answer. Answer: 36 to 36

Solution

Related Formula

At steady state, a capacitor acts as an open circuit to DC current. The charge on a capacitor is:

Q = C Δ V

Core Logic

When node A and node B are connected by a wire, they reach the same electrical potential (VA = VB = VM).

At DC steady state, capacitors block current, so current only flows through the resistors from the 9 V source to ground:

  • The 6 Ω resistor is connected between 9 V and node M.
  • The 3 Ω resistor is connected between node M and ground.
  • Hence, the equivalent series resistance for the DC current path is:

Req = 6 + 3 = 9 Ω

The steady state current is:

I = VReq = 9 V9 Ω = 1 A

Simplified equivalent steady-state circuit for Q56
The diagram displays a bridge-like network containing a 6 Ohm resistor, 3uF capacitor, 6uF capacitor, and 3 Ohm resistor powered by a 9V supply.

Step 1: Calculate the Potential Difference and Charge

The potential at node M (VM) is:

VM = I × 3 Ω = 1 A × 3 Ω = 3 V

The 6 capacitor is connected between the 9 V source and node B (which is at potential VM = 3 V).

Thus, the potential difference across the 6 capacitor is:

Δ V₆ = 9 V - 3 V = 6 V

The charge stored in the 6 capacitor is:

Q = C Δ V = 6 × 6 V = 36

Thus, the charge stored is 36.

Pattern Recognition

Shorting A and B makes the network a simple voltage divider for resistors at steady state. Once potential of the middle node is found (3 V), the capacitor charge is calculated instantly using Q = C Δ V.

Chapter Mix

Class 12 Physics: Electrostatic Potential and Capacitance

Q57 jee_main_2024_30_jan_morning Energy Loss in Capacitors
A capacitor of capacitance C and potential V has energy E. It is connected to another capacitor of capacitance 2C and potential 2V. Then the loss of energy is (x)/(3)E, where x is ________.
Numerical Answer. Answer: 2 to 2

Solution

Related Formula
E = (1)/(2) C V² Δ E = (1)/(2) (C₁ C₂)/(C₁ + C₂) (V₁ - V₂)²
Core Logic

When two charged capacitors are connected in parallel, charge redistributes until they reach a common potential. During this redistribution, energy is dissipated as heat, strictly governed by the standard loss formula.

Step 1: Assign Values

Initial energy of first capacitor: E = (1)/(2) C V² Capacitor 1: C₁ = C, V₁ = V Capacitor 2: C₂ = 2C, V₂ = 2V

Step 2: Calculate Energy Loss
Δ E = (1)/(2) ((C)(2C))/(C + 2C) (V - 2V)² Δ E = (1)/(2) (2C²)/(3C) (-V)² Δ E = (1)/(2) ((2C)/(3)) V² Δ E = (2)/(3) ((1)/(2) C V²) Δ E = (2)/(3) E
Step 3: Match the Pattern

Given loss is (x)/(3)E. Comparing, we get x = 2.

Pattern Recognition

The loss formula Δ E = (1)/(2) Ceq(Δ V)² elegantly bypasses recalculating common potential Vc and summing final state energies.

Chapter Mix

Class 12 Physics: Electrostatic Potential and Capacitance

More Electrostatic Potential and Capacitance Questions — jee_main_2025_28_jan_morning

Practice all Electrostatic Potential and Capacitance previous-year questions →

Rankbit System
JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%) | JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%)