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Saturday, 31 October

JEE Main 2021 · PhysicsNumerical answerNumerical valueEasyCalculation

JEE Main 17 March 2021, Shift 2, Physics Q21

Question 21 of 90 in this shift, Physics question 21 of 30, Section B.

A 2 μ\muF capacitor C1\mathrm{C_1} is first charged to a potential difference of 10 V using a battery. Then the battery is removed and the capacitor is connected to an uncharged capacitor C2\mathrm{C_2} of 8 μ\muF. The charge in C2\mathrm{C_2} on equilibrium condition is ____________ μ\muC. (Round off to the Nearest Integer)

The figure, in words

Circuit: a rectangular loop with a 10 V battery on the left side, capacitor C1 (labelled 2 microfarad) in the middle vertical branch and capacitor C2 (labelled 8 microfarad) on the right side; switch S1 in the top wire between the battery and C1, switch S2 in the top wire between C1 and C2.

Official answer

16

NTA final key.

Chapter
Electrostatic Potential and Capacitance
Topic
Parallel Plate Capacitors
Idea tested
Charge Sharing and Heat Loss

Same idea in other shifts

Asked 12× in all
  1. 3 Apr 2025, Shift 2 · Q38Using a battery, a 100 pF capacitor is charged to 60 V and then the battery is removed. After that, a second uncharged capacitor is…EasySingle correct
  2. 1 Feb 2024, Shift 1 · Q40Two identical capacitors have same capacitance C. One of them is charged to the potential V and other to the potential 2V. The negative…MediumSingle correct
  3. 30 Jan 2024, Shift 1 · Q55A capacitor of capacitance C and potential V has energy E. It is connected to another capacitor of capacitance 2 C and potential 2 V. Then…MediumNumerical value
  4. 8 Apr 2023, Shift 2 · Q55A 600 pF capacitor is charged by 200 V supply. It is then disconnected from the supply and is connected to another uncharged 600 pF…MediumNumerical value
  5. 11 Apr 2023, Shift 1 · Q41A parallel plate capacitor of capacitance 2 F is charged to a potential V, The energy stored in the capacitor is E1E_1. The capacitor is…EasySingle correct
  6. 26 Jun 2022, Shift 1 · Q40Two capacitors having capacitance C1C_1 and C2C_2 respectively are connected as shown in figure. Initially, capacitor C1C_1 is charged to…EasyDiagram basedHas a figure
  7. 27 Jun 2022, Shift 1 · Q57A capacitor of capacitance 50 pF is charged by 100 V source. It is then connected to another uncharged identical capacitor. Electrostatic…EasyNumerical value
  8. 2 Sep 2020, Shift 1 · Q23A 5 μF5\ \mu\mathrm{F} capacitor is charged fully by a 220 V supply. It is then disconnected from the supply and is connected in series to…MediumNumerical value

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.