5. The following circuit improves the loading-induced nonlinearity in a potentiometer.
$(1-\alpha)R_T$
$R_m$
$V_r$
$\alpha R_T$
$V_m$
$R_m$
(a) Express $v_m$ with $V_r$, $\alpha$, $k$. (Assume that $k = R_m/R_T$)
(b) Find the relative error $\epsilon = (v_m - v_o)/v_o$ and plot $\epsilon$ against the change in $\alpha$.
(c) When the relative error becomes zero?