The insulating material placed between the conducting plates of a capacitor is a(n) .

As we know that insulators are known as DIELECTRIC which is placed between plates of capacitor

Explanation:

As we know that dielectric medium when placed between the plates of capacitor then the capacitance is given as

so here we know that

k = dielectric constant

so here the capacitance of the capacitor will increase by k times as we place a insulating material between the plates of capacitor

So correct answer will be

The insulating material placed between the conducting plates of a capacitor is a DIELECTRIC