Electrostatics 5 Question 14

15. A parallel plate capacitor is of area 6 cm2 and a separation 3 mm. The gap is filled with three dielectric materials of equal thickness (see figure) with dielectric constants K1=10, K2=12 and K3=14. The dielectric constant of a material which give same capacitance when fully inserted in above capacitor, would be

(Main 2019, 10 Jan I)

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(a) 4

(b) 36

(c) 12

(d) 14

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Answer:

Correct Answer: 15. (c)

Solution:

  1. In the given arrangement, capacitor can be viewed as threedifferent capacitors connected in parallel as shown below,

So, equivalent capacity of the system is

Ceq=C1+C2+C3Kε0Ad=K1ε0A/3d+K2ε0A/3d+K3ε0A/3dK=K13+K23+K33 Here, K1=10,K2=12 and K3=14 So, K=10+12+143K=12



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