(a(i))[3]
Explain why point P is described as a virtual earth.
(a(ii))[2]
Calculate the amplifier’s gain.
(b)[3]
When the op-amp is saturated, the potential difference across the LED is $2.3\,\text{V}$. Calculate the minimum value of resistor $R$ needed to limit the LED current to $30\,\text{mA}$.