A parallel plate capacitor is formed by two plates each of area 30$\pi cm2 separated by 1 mm. A material of dielectric strength 3.6 \times 107 Vm-1 is filled between the plates. If the maximum charge that can be stored on the capacitor without causing any dielectric breakdown is 7 \times 10-6C, the value of dielectric constant of the material is :
[Use {1 \over {4\pi {\varepsilon _0}}} = 9 \times {10^9} Nm2 C-$2]