Electrostatics Question 87

Question: The capacitance of an air filled parallel plate capacitor is $ 10\mu \mu F $ . The separation between the plates is doubled and the space between the plates is then filled with wax giving the capacitance a new value of$ 40\times {{10}^{-12}}farads $ . The dielectric constant of wax is [AMU 1995]

Options:

A) 12.0

B) 10.0

C) 8.0

D) 4.2

Show Answer

Answer:

Correct Answer: C

Solution:

$ C _{1}=\frac{{\varepsilon _{0}}A}{d} $ and $ C _{2}=\frac{K{\varepsilon _{0}}A}{2d} $

therefore $ \frac{C _{2}}{C _{1}}=\frac{K}{2} $

therefore $ \frac{40\times {{10}^{-12}}}{10\times {{10}^{-12}}}=\frac{K}{2} $

therefore K = 8



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