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JEE Main 2023 (31 Jan, Shift 2) · Dielectrics

Dielectrics question from JEE Main 2023 (31 Jan, Shift 2)

Q60JEE Main 2023 · 31 JAN · SHIFT 2Difficult

Dielectrics

Two parallel plate capacitors C1C_1 and C2C_2 each having capacitance of 10 μF10\ \mu\text{F} are individually charged by a 100 V D.C. source. Capacitor C1C_1 is kept connected to the source and a dielectric slab is inserted between its plates. Capacitor C2C_2 is disconnected from the source and then a dielectric slab is inserted in it. Afterwards the capacitor C1C_1 is also disconnected from the source and the two capacitors are finally connected in parallel combination. The common potential of the combination will be ________ V.

(Assuming Dielectric constant =10= 10)

Numerical answer type. Work it out, then open the answer.

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Answer: 55

  1. C1C_1 stays connected: C1′=100 μFC_1' = 100\ \mu\text{F} at 100 V, so Q1=10000 μCQ_1 = 10000\ \mu\text{C}.
  2. C2C_2 disconnected first: Q2=10×100=1000 μCQ_2 = 10 \times 100 = 1000\ \mu\text{C}, C2′=100 μFC_2' = 100\ \mu\text{F}.
  3. In parallel: V=Q1+Q2C1′+C2′=11000200=55 VV = \frac{Q_1 + Q_2}{C_1' + C_2'} = \frac{11000}{200} = 55\text{ V}
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