$10.$ Consider a DC shunt generator driven at $1000$ rpm $.$ The armature and field circuit resistance are $\backslash (0\mathrm{.}4\backslash$Omega $\backslash )$ and $\backslash (60\backslash$Omega $\backslash )$ respectively. The generated emf and field current characteristics obtained at $1000$ rpm are:

Determine: $($i$)$ the voltage to which it will excite on open circuit. $($ii$)$ the approximate value of the critical resistance of the shunt circuit. $($iii$)$ the terminal potential difference and load current for a load resistance of $\backslash (4\backslash$Omega $\backslash ).$