Two cells are connected in opposition as shown. Cell E_1 is of 8 V emf and 2 Ω internal resistance; the cell E_2 is of 2 V emf and 4 Ω internal…

Two cells are connected in opposition as shown. Cell $\displaystyle \mathrm{E}_1$ is of $\displaystyle 8$ V emf and $\displaystyle 2 \Omega$ internal resistance; the cell $\displaystyle \mathrm{E}_2$ is of $\displaystyle 2$ V emf and $\displaystyle 4 \Omega$ internal resistance. The terminal potential difference of cell $\displaystyle \mathrm{E}_2$ is $\displaystyle \_\_\_\_$ V.