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JEE Main 2026 (2 Apr, Shift 1) · Dielectrics

Dielectrics question from JEE Main 2026 (2 Apr, Shift 1)

Q11JEE Main 2026 · 2 APR · SHIFT 1Easy

Dielectrics

A parallel plate air capacitor has a capacitance CC. When it is half filled as shown in figure with a dielectric constant K=5K = 5, the percentage increase in the capacitance is ________.

Figure

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Answer: (b)

K = 5 : 10Cair : 2CseriesC' = 5C/3
  1. The dielectric fills half the gap (layer parallel to the plates), so the two layers are in series.
  2. Air layer: 2C2C; dielectric layer: 2KC=10C2KC = 10C.
  3. C′=2C×10C12C=5C3C' = \frac{2C \times 10C}{12C} = \frac{5C}{3}.
  4. Increase =5C/3−CC×100=66.67%= \frac{5C/3 - C}{C} \times 100 = 66.67\%.
  5. So the answer is (b) 66.67.
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