A parallel-plate capacitor is constructed of two square plates, size \(L \times L\), separated by distance \(d\). The plates are given charge \(\pm Q\). What is the ratio \(E_{\mathrm{f}} / E_{\mathrm{i}}\) of the final electric field strength \(E_{\mathrm{f}}\) to the initial electric field strength \(E_{\mathrm{i}}\) if:

a. \(Q\) is doubled?

b. \(L\) is doubled?

c. \(d\) is doubled?