JEE Main 2024 · PhysicsMultiple choiceSingle correctMediumCalculation

JEE Main 1 February 2024, Shift 1, Physics Q40

Question 40 of 90 in this shift, Physics question 10 of 30, Section A.

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 :

(1) $\frac{1}{2}CV^2$
(2) $\frac{1}{4}CV^2$ Official answer
(3) $2\,CV^2$
(4) $\frac{3}{4}CV^2$

Official answer

Option 2

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

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
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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
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 $E_1$ . The capacitor is…EasySingle correct
26 Jun 2022, Shift 1 · Q40Two capacitors having capacitance $C_1$ and $C_2$ respectively are connected as shown in figure. Initially, capacitor $C_1$ is charged to…EasyDiagram basedHas a figure
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
17 Mar 2021, Shift 2 · Q21A 2 $\mu$ F capacitor $\mathrm{C_1}$ is first charged to a potential difference of 10 V using a battery. Then the battery is removed and…EasyNumerical valueHas a figure
2 Sep 2020, Shift 1 · Q23A $5\ \mu\mathrm{F}$ 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. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.