Two parallel plate capacitors, each of capacitance `40 muF` , are connected is series. The space between the plates of one capacitor is filled with a dielectric material of dielectric constant K =4. Find the equivalent capacitacne of the system.

Explanation

The capacitance of the capacitor with the dielectric is s`
` C_1 = KC_0 = 4X 40 muF = 160 mu F`
`. The other capacitor has capacitance `
`C_2 = 40 um F`
`. As they are connected in series, the equivalent capacitance is `
` C = (C_1 C_2)/(C_1+C_2) = ((160 muF)(40 muF))/(200muF) = 32muF`
`.