Question

What will be area of pieces of paper in order to make a paper condenser of capacitance $0.04\mu F$, if the dielectric constant of paper is $2.5$ and its thickness is $0.025mm$ ?

• A. $1m^2$
• B. $2\times {10}^{-3}{m}^2$
• C. $4.51\times {10}^3{m}^2$
• D. ${10}^{-3}{m}^2$

Answer 1

The correct option is C $4.51\times {10}^3{m}^2$

For paper condenser we will use the expression of capacitance of parallel plate condenser with dielectric.
$C=\frac{Ak{ϵ}_0}{d}$
$A=\frac{Cd}{k{ϵ}_0}=\frac{0.04\times {10}^{-6}\times 0.025\times {10}^{-3}}{2.5\times 8.854\times {10}^{-12}}=4.51\times {10}^3{m}^2$