The space between the plates of a parallel plate capacitor is filled with a mica sheet of thickness \(1 \times 10^{-3} \mathrm{~m}\) and a fiber sheet of thickness \(0.5 \times 10^{-3} \mathrm{~m}\). The dielectric constants of mica and fiber are 8 and 2.5 respectively. If the fiber breaks down at an electric field of \(6.4 \times 10^{-6} \mathrm{Vm}^{-1}\) then the maximum voltage that can be applied to the capacitor is

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.