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NEET 2020 (Phase 2) · Dielectrics

Dielectrics question from NEET 2020 (Phase 2)

Q89NEET 2020 · PHASE 2Medium

Dielectrics

A parallel plate capacitor having cross-sectional area AA and separation dd has air in between the plates. Now an insulating slab of same area but thickness d/2d/2 is inserted between the plates as shown in figure having dielectric constant K(=4)K(=4). The ratio of new capacitance to its original capacitance will be,

Figure

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Answer: (c)

  1. Air d2\frac{d}{2} and slab d2\frac{d}{2} in series: C=ϵ0Ad2+d2KC=\frac{\epsilon_0A}{\frac{d}{2}+\frac{d}{2K}}
  2. With K=4K=4: C=ϵ0A5d8=85C0C=\frac{\epsilon_0A}{\frac{5d}{8}}=\frac{8}{5}C_0
  3. So the answer is (c) 8:58:5.
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