(a)[3]
State three characteristics of an ideal op-amp.
(b(i))
In one use of the comparator, $V_2$ is held fixed at $+1.5\,\text{V}$. Fig. 9.2 shows how the potential $V_1$ varies with time $t$. The potential $V_2$ is also displayed.
(b(ii))[3]
Two light-emitting diodes (LEDs) R and G are linked to the op-amp output in Fig. 9.1 so that R is lit for a longer period than G. On Fig. 9.1, draw the symbols of the two diodes connected to the op-amp output and label them R and G.