a$)$ Explain what is process load and process lag $[6$ Marks$]$ b$)$ Given a proportional controller that the controlled variable is a process temperature with a range of $50$C $()$to $100$C $(),$ set$-$point, SP of $75$C and proportional gain Kp of $0\mathrm{.}5.$ Under normal condition, the set$-$point is maintained with an controller output, $$ of $50\%.$ If a load change which requires a $60\%$ controller ou