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Capacitor question

2021 · 17 Mar · Shift 2 · Q66
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  5. /2021 · 17 Mar · Shift 2 · Q66

Capacitor question

2021 · 17 Mar · Shift 2 · Q66

JEE MainPhysicsCapacitorNumerical+4 / −1
A 2 μ\muμ F capacitor C1 is first charged to a potential difference of 10V using a battery. Then the battery is removed and the capacitor is connected to an uncharged capacitor C2 of 8 μ\muμ F. The charge in C2 on equilibrium condition is ‾μ\underline{\hspace{2cm}}\mu​μ C. (Round off to the Nearest Integer) JEE Main 2021 (Online) 17th March Evening Shift Physics - Capacitor Question 91 English
Numerical answer
View written solutionFree

Correct answer: 16

  1. Initial charge on C1C_1C1​

Given:

  • C1=2 μFC_1 = 2\,\mu FC1​=2μF
  • Initial potential V=10 VV = 10\,VV=10V

So the initial charge on C1C_1C1​ is

Qinitial=C1V=2×10=20 μCQ_{\text{initial}} = C_1 V = 2\times 10 = 20\,\mu CQinitial​=C1​V=2×10=20μC

Since the battery is removed, this total charge is conserved when C1C_1C1​ is connected to the uncharged capacitor C2C_2C2​.

  1. Capacitors connected together

Given:

  • C2=8 μFC_2 = 8\,\mu FC2​=8μF
  • Initially uncharged

After connection, both capacitors come to the same final potential VfV_fVf​.

Total capacitance:

Ceq=C1+C2=2+8=10 μFC_{\text{eq}} = C_1 + C_2 = 2 + 8 = 10\,\mu FCeq​=C1​+C2​=2+8=10μF

Using charge conservation:

Qtotal=CeqVfQ_{\text{total}} = C_{\text{eq}} V_fQtotal​=Ceq​Vf​ 20=10 Vf20 = 10\,V_f20=10Vf​ Vf=2 VV_f = 2\,VVf​=2V
  1. Charge on C2C_2C2​ at equilibrium
Q2=C2Vf=8×2=16 μCQ_2 = C_2 V_f = 8\times 2 = 16\,\mu CQ2​=C2​Vf​=8×2=16μC
  1. Final answer

The charge on C2C_2C2​ in equilibrium is

16 μC\boxed{16\,\mu C}16μC​

Rounded to the nearest integer: 16\boxed{16}16​.

  1. Comparison with stored answer

Stored correct answer = 161616

Our derived answer also = 161616, so they agree.

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