At anode $\mathrm{Cu} \rightarrow \mathrm{Cu}^{2+}+2 \mathrm{e}^{-}$
At cathode $2 \mathrm{Ag}^{+}+2 \mathrm{e}^{-} \rightarrow 2 \mathrm{Ag}$
Cell reaction $\rightarrow \mathrm{Cu}+2 \mathrm{Ag}^{+} \rightarrow \mathrm{Cu}^{2+}+2 \mathrm{Ag}$ $$ \begin{aligned} & E_{\mathrm{cell}}=E_{\mathrm{cel}}^0-\frac{0.06}{2} \log \frac{\left[\mathrm{Cu}^{2+}\right]}{\left[\mathrm{Ag}^{+}\right]^2} \\ & 0.43=E_{\mathrm{cel}}^0-\frac{0.06}{2} \log \frac{[0.001]}{(0.01)^2} \\ & E_{\mathrm{cel}}^0=0.46 \\ & E_{\mathrm{cel}}^0=E_{\mathrm{Ag}^{\prime} / \mathrm{Ag}}^0-E_{\mathrm{Cu}^{2+} / \mathrm{Cu}}^0 \\ & 0.46=0.80-E_{\mathrm{Cu}^{2+} / \mathrm{Cu}}^0 \\ & E_{\mathrm{Cu}^{2-} / \mathrm{Cu}}^0=0.34 \mathrm{volt} \\ & E_{\mathrm{Cu}^{2+} / \mathrm{Cu}}^0=34 \times 10^{-2} \end{aligned} $$