Question

The area of the plates of a parallel plate condenser is $A$and the distance between the plates is $10mm$. There are two dielectric sheets in it, one of dielectric constant 10 and thickness $6mm$ and the other of dielectric constant 5 and thickness $4mm$. The capacity of the condenser is

• A. $\frac{12}{35}\varepsilon_{0}A$
• B. $\frac{2}{3}\varepsilon_{0}A$
• C. $\frac{5000}{7}\varepsilon_{0}A$
• D. $1500\mspace{6mu}\varepsilon_{0}A$

Answer 1

Answer: (C)

$\frac{5000}{7}\varepsilon_{0}A$

Answer 2

$C = \frac{\varepsilon_{0}A}{\left( \frac{t_{1}}{k_{1}} + \frac{t_{2}}{k_{2}} \right)} = \frac{\varepsilon_{0}A}{\frac{6 \times 10^{- 3}}{10} + \frac{4 \times 10^{- 3}}{5}} = \frac{5000}{7}\varepsilon_{0}A$