# Question #a71ed

May 30, 2016

$2.598 \text{ uf}$, rounded to three decimal places

#### Explanation:

We know that capacitance of a parallel plate capacitor is given by the expression
$C = \epsilon \frac{A}{d}$
Where $\epsilon$ is absolute permittivity of the dielectric, $A$ is area of plate overlap and $d$ is the distance between the plates.
Absolute permittivity of air$= 1.0006$
Absolute permittivity of polystyrene$= 2.6$
Therefore,
${C}_{\text{polystyrene"=C_"air"xx"Absolute permittivity of polystyrene"/"Absolute permittivity of air}}$
Inserting various values
${C}_{\text{polystyrene"=1 xx2.6/1.0006=2.598" uf}}$, rounded to three decimal places

Average dielectric constant of polystyrene as $2.6$, Ref