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A dipole with two electric charges of 2 µC magnitude each, with separation distance 0.5 µm, is placed between the plates of a capacitor such that its axis is parallel to an electric field established between the plates when a potential difference of 5 V is applied. Separation between the plates is 0.5 mm. If the dipole is rotated by 30^circ from the axis, it tends to realign in the direction due to a torque. The value of torque is : [cite: 58, 59, 60]

Solution & Explanation

### Related Formula E = fracVd [cite: 736] tau = pEsintheta [cite: 737] p = q cdot a [cite: 738] ### Core Logic First, calculate the electric field magnitude E between the capacitor plates: [cite: 58, 736] E = frac50.5 times 10^-3 = 10^4\ textV/m [cite: 58, 59, 736] Next, evaluate the dipole moment p: [cite: 58, 738] p = (2 times 10^-6\ textC) times (0.5 times 10^-6\ textm) = 1 times 10^-12\ textCcdottextm [cite: 58, 740] Now find the torque when rotated by theta = 30^circ: [cite: 59, 737] tau = (1 times 10^-12) times 10^4 times sin 30^circ = 10^-8 times frac12 = 5 times 10^-9\ textNcdottextm [cite: 743] ### Pattern Recognition Always convert parameters to pristine standard SI units before applying electrostatic expressions (0.5\ mutextm = 5 times 10^-7\ textm and 0.5\ textmm = 5 times 10^-4\ textm) to secure zero conversion error[cite: 58, 59, 736, 738]. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Physics: Electrostatics

Reference Study Guides

More Electrostatics Previous-Year Questions — Page 4

Q18 2025 Electric Field Intensity
Two infinite identical charged sheets and a charged spherical body of charge density ' ho' are arranged as shown in figure. Then the correct relation between the electrical fields at A, B, C and D points is :
Electric Field Intensity diagram for Q18 - JEE Main 2025 Morning
The figure illustrates two parallel infinite charged plates with a uniform charge density along with an embedded solid spherical charge mass distributed near reference measurement tags labeled A, B, C, and D.
  • A. vecE_A=vecE_B; vecE_C=vecE_D
  • B. vecE_A>vecE_B; vecE_C=vecE_D
  • C. vecE_C evecE_D; vecE_A>vecE_B
  • D. |vecE_A|=|vecE_B|; vecE_C>vecE_D

Solution

### Related Formula Superposition of electric field tracks: vecE*textnet = vecE*textsheets + vecE*textsphere ### Core Logic Evaluate local positional tracking parameters: * The fields due to the infinite plates add or subtract symmetrically across regions. * The central sphere introduces a radially varying vector component (E propto frac1r^2 outside or E propto r inside) whose structural mapping changes direction between symmetric tracking tags. * At points C and D, the directional orientation components of the spherical vector directly contrast each other, meaning vecE_C e vecE_D. * Sifting structural balances reveals field amplification profiles near point A exceeding local parameters at B due to positive alignment additions, so vecE_A > vecE_B. ### Pattern Recognition Vector fields demand both magnitude and coordinate direction vector compliance. Symmetries can ensure equal scalar values while completely breaking vector equivalence. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Physics: Electrostatics
Q19 2025 Torque on an Electric Dipole
Two small spherical balls of mass 10g each with charges -2mumathrmC and 2mumathrmC, are attached to two ends of very light rigid rod of length 20 cm. The arrangement is now placed near an infinite non-conducting charge sheet with uniform charge density of 100mumathrmC/m^2 such that length of rod makes an angle of 30^circ with electric field generated by charge sheet. Net torque acting on the rod is: (Take epsilon*o = 8.85times10^-12mathrmC^2/mathrmNm^2)
  • A. 112 Nm
  • B. 1.12 Nm
  • C. 2.24 Nm
  • D. 11.2 Nm

Solution

### Related Formula Electric field due to an infinite non-conducting sheet: E = fracsigma2epsilon_0 Torque on an electric dipole configuration: tau = p E sintheta where p = q cdot d (dipole moment). ### Core Logic Given parameters: * Charge, q = 2 times 10^-6mathrm~C * Separation length, d = 20mathrm~cm = 0.2mathrm~m * Charge density, sigma = 100 times 10^-6mathrm~C/m^2 * Orientation angle, theta = 30^circ ### Step 1: Compute Field and Torque Value First, evaluate the field matrix strength value: E = frac100 times 10^-62 times 8.85 times 10^-12 Now insert everything into the torque expression: tau = (q cdot d) cdot E cdot sin(30^circ) tau = left[ (2 times 10^-6) cdot (0.2) ight] cdot left[ frac100 times 10^-62 times 8.85 times 10^-12 ight] cdot left( frac12 ight) tau = frac108.85 approx 1.12mathrm~Nm
Dipole torque vector field distribution alignment for Q19 - JEE Main 2025 Morning
Dipole torque vector field distribution alignment for Q19 - JEE Main 2025 Morning
### Pattern Recognition Equal and opposite charges separated by a fixed distance form an electric dipole. The torque in a uniform electric field depends exclusively on the dipole moment value, field strength, and the sine of the orientation angle. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Physics: Electrostatics
Q24 2025 Combination of Capacitors
Four capacitor each of capacitance 16mumathrmF are connected as shown in the figure. The capacitance between points A and B is: (in mumathrmF).
Four capacitor network schematic for Q24 - JEE Main 2025 Morning
The figure details an interconnected array layout composed of four identical storage components branching outwards between primary measurement terminals A and B.
Numerical Answer. Answer: 64 to 64

Solution

### Related Formula Equivalent capacitance for a parallel configuration network: C_texteq = C_1 + C_2 + C_3 + dots ### Core Logic By tracing node connectivity potentials carefully throughout the short-circuit wire paths, we can label the plates of all four capacitors.
Node mapping potential re-layout diagram for Q24 - JEE Main 2025 Morning
The figure details an interconnected array layout composed of four identical storage components branching outwards between primary measurement terminals A and B.
Redrawing the circuit connection matrix map reveals that all 4 capacitors are connected directly in parallel between node terminal A and node terminal B. ### Step 1: Calculate Equivalent Value Since they are in parallel: C_texteq = 4 cdot C Given each individual element carries C = 16mumathrmF: C_texteq = 4 times 16 = 64mumathrmF
Node mapping potential re-layout diagram for Q24 - JEE Main 2025 Morning
The figure details an interconnected array layout composed of four identical storage components branching outwards between primary measurement terminals A and B.
### Pattern Recognition Shorting loops across alternate terminals routinely unravels interlocking rows back into straightforward parallel grids. Always trace and label nodes first. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Physics: Electrostatics
Q1 2025 Electrostatic Shielding
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): The outer body of an air craft is made of metal which protects persons sitting inside from lightning-strikes. [cite: 12] Reason (R): The electric field inside the cavity enclosed by a conductor is zero. [cite: 13] In the light of the above statements, chose the most appropriate answer from the options given below: [cite: 14]
  • A. Both (A) and (R) are correct and (R) is the correct explanation of (A) [cite: 15]
  • B. (A) is correct but (R) is not correct [cite: 16]
  • C. Both (A) and (R) are correct but (R) is not correct explanation of (A) [cite: 17]
  • D. (A) is not correct but (R) is correct [cite: 18]

Solution

### Core Logic According to electrostatic shielding, the electric field inside a cavity of a conductor is always zero, regardless of the size and shape of the cavity and regardless of any charges located outside or on the conductor's surface[cite: 660]. Therefore, when lightning strikes a metal aircraft, the entire charge stays on the outer metallic surface and flows down without producing an electric field inside, keeping passengers safe[cite: 12]. ### Step 1: Statement Evaluation * **Assertion (A):** Correct, passengers are protected from lightning because of the metallic body shield [cite: 12]. * **Reason (R):** Correct, the field inside a cavity of a conductor is zero [cite: 13]. * **Explanation:** Since the zero field property is precisely why passengers are protected, (R) correctly explains (A)[cite: 15]. ### Pattern Recognition Metallic shell / shield configuration always establishes E_textinside = 0[cite: 660]. This shielding mechanism directly underpins safety features in lightning scenarios for cars and airplanes. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Physics: Electrostatics

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