Question $3(10$ marks$)$

Below is a circuit diagram of a temperature sensor based on a LM$393$ operational amplifier $($Op$-$Amp$)$ IC$.$ Please determine the values of R$1$ and R$2$ of the potentiometer to satisfy the following condition. LED$2$ will be turned on if the temperature is below $\backslash (0^\{\backslash$circ$\}\backslash$mathrm$\{$C$\}\backslash ).$

$($a$)$ Please explain what mode the Op$-$Amp in this circuit is working on$.$ Is it Closed loop or Open loop? $(1$ mark$)$

$($b$)$ What is the input and output resistance values of an ideal Op$-$Amp? $(2$ marks$)$

$($c$)$ What are the possible voltage values at Pin$\_1$OUT? $(2$ marks$)$

$($d$)$ Determine the values of R$1$ and R$2.($Keep two decimal places$)$ Detailed steps are required. $(5$ marks$)$