Q$1$: For the circuit shown in Figure$-1,$

$($a$)$ Calculate the equivalent resistance of the circuit, $\backslash (\backslash$mathrm$\{$R$\}\_\{\backslash$mathrm$\{$AB$\}\}\backslash )$ at the terminals A and B $.[10]$

$($b$)$ When $50$ V dc source is switched at terminals $\backslash (\backslash$mathrm$\{$A$\}-\backslash$mathrm$\{$B$\}\backslash ),$ solve for the voltage $\backslash (\backslash$mathrm$\{$V$\}\_\{1\}\backslash )$ at the location shown.

$[10]$

Figure$-1$ could you explain how you find out the Req thank you