Verified Solution • 2025–26 Session moderate

QNEET-2016-Ph-1182: NEET 2016 Physics - Class 12 NEET-2016-Ph-1182 Solution: A parallel-plate capacitor of area a plate separation d and…

A parallel-plate capacitor of area a plate separation d and capacitance C is filled with four dielectric materials having dielectric constants k1k2k3k_1 k_2 k_3 and k4k_4 as shown in the figure. If a single dielectric material is to be used to have the same capacitance C in this capacitor then its dielectric constant k is given by k=k1+k2+k3+3k4k = k_1 + k_2 + k_3 + 3k_4 k=23(k1+k2+k3)+2k4k = \frac{2}{3}(k_1+k_2+k_3)+2k_4 2k=3k1+k2+k3+1k4\frac{2}{k} = \frac{3}{k_1+k_2+k_3}+\frac{1}{k_4} 1k=1k1+1k2+1k3+32k4\frac{1}{k} = \frac{1}{k_1}+\frac{1}{k_2}+\frac{1}{k_3}+\frac{3}{2k_4}

Multiple Choice Options

  • A k = k 1 + k 2 + k 3 + 3k 4
  • B k = 23{2 \over 3} 3 2 _ (k 1 + k 2 + k 3 ) + 2k 4
  • C 2k{2 \over k} k 2 _ = 3k1+k2+k3+1k4{3 \over {{k_1} + {k_2} + {k_3}}} + {1 \over {{k_4}}} k 1 _ + k 2 _ + k 3 _ 3 _ + k 4 _ 1 _
  • D 1k{1 \over k} k 1 _ = 1k1+1k2+1k3+32k4{1 \over {{k_1}}} + {1 \over {{k_2}}} + {1 \over {{k_3}}} + {3 \over {2{k_4}}} k 1 _ 1 _ + k 2 _ 1 _ + k 3 _ 1 _ + 2 k 4 _ 3 _

Step-by-Step Verified Solution

Here, C 1 = 2 _ 0 k 1 A 3 d , C 2 = 2 _ 0 k 2 A 3 d C 3 = 2 _ 0 k 3 A 3 d , C 4 = 2 _ 0 k 4 A d Given system of C 1 , C 2 , C 3 and C 4 can be simplified as _ 1 C A B = 1 C 1 + C 2 + C 3 + 1 C 4 Suppose, C A B = k _ 0 A d C A B = 1 k ( _ 0 A d ) = 1 2 3 _ 0 A d ( k 1 + k 2 + k 3 ) + 1 2 _ 0 A d k 4 _ 1 k = 1 2 ( k 1 + k 2 + k 3 ) + 1 2 k 4 _ 2 k = 3 k 1 + k 2 + k 3 + 1 k 4

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