(a)[4]
State any four properties of an ideal operational amplifier.
(b)[3]
A comparator circuit containing an ideal op-amp is illustrated in Fig. 9.1. The change with time $t$ of the input potential $V_{IN}$ is shown in Fig. 9.2. On the axes of Fig. 9.2, draw a graph to represent the change with time $t$ of the output potential $V_{OUT}$.
(c)[3]
Two light-emitting diodes (LEDs) are to be used to show the output potential $V_{OUT}$. A red-emitting diode is to show when $V_{OUT}$ is positive, and a green-emitting diode is to show when $V_{OUT}$ is negative. Complete Fig. 9.3 so that the two LEDs are connected to the op-amp output. Label each LED with the colour of light that it emits.