Exams › JEE Advanced › Physics
Two identical square metal plates, each of side 1 m, are held 0.01 m apart (like a parallel-plate capacitor) with one pair of edges perpendicular to and touching an oil surface. The plates are connected to a 500 V battery. They are then lowered vertically into the insulating oil at a steady speed of 0.001 m/s. Calculate the current drawn from the battery during this process. (Dielectric constant of oil K = 11, epsilon₀ = 8.85 * 10⁻¹² C² N⁻¹ m⁻¹) Express in nanoampere.
- 40.7 nA
- 45.0 nA
- 36.3 nA
- 48.7 nA
Correct answer: 40.7 nA
Solution
As the plates descend, the oil-filled portion grows at rate v = 0.001 m/s. The capacitance increases at a constant rate dC/dt = epsilon₀ * (K-1) * (1 m width) * v / d. The battery current is I = V * dC/dt.
Related JEE Advanced Physics questions
- A particle with charge -q and mass m revolves in a circular path of radius r around an infinitely long charged wire with linear charge density +λ. What is the time period of its motion?
- What is the value of the electrostatic potential at point H?
- The electric potential V varies with distance x from a fixed point as follows: V = 5 V for 0 <= x < 10 m, then V decreases linearly from 5 V at x = 10 m to -10 V at x = 20 m. The electric field at x = 13 m is:
- Two capacitors are connected in a circuit with two batteries and a switch S. The system is in steady state with S open. When S is closed, which of the following statements correctly describes the energy exchange?
- In a capacitor bridge circuit, four capacitors C1, C2, C3, and C4 are connected in a bridge configuration with an EMF source E. Capacitor C1 is in the top-left arm, C2 in the top-right arm, C3 in the bottom-left arm, and C4 in the bottom-right arm. Points P and Q are the mid-points (junctions). Find the potential difference V_P - V_Q.
- An isolated charged spherical soap bubble of radius r has the pressure inside equal to atmospheric pressure outside. The surface tension of the soap solution is T. If the total charge on the bubble can be written as N*pi*r*sqrt(2*T/epsilon0), find the integer value of N.
⚔️ Practice JEE Advanced Physics free + battle 1v1 →