(a(i))[1]
State the name given to this circuit.
(a(ii))[3]
Explain why point $P$ is described as a virtual earth.
(b(i))[3]
The input potential $V_{IN}$ and the switch setting are changed. At every switch setting, the voltmeter reading is $1.0\,\text{V}$. Complete Fig. 11.3 for the switch settings shown.
(b(ii))[1]
Using your answers in (i), suggest one use for the circuit in Fig. 11.2.