(a)      Explain with the aid of a block diagram, the operation of a closed
          loop system.
(b)     Classify the following into open and closed loop system:
          (i)      water heater;
          (ii)      electric pressing iron;
          (iii)     remote control device;
          (iv)     microwave oven;
          (v)      switch.
 
The expected answers were:
(a)

In a closed loop control system, part of the output is used to effect changes of the controlled variable.

(b)