Negative feedback may be used in amplifier circuits. State
what is meant by negative feedback,
two effects of negative feedback on an amplifier incorporating an operational amplifier (op-amp).
The figure below is a circuit for an amplifier that is used with a microphone.
The output potential difference 
is 
when the potential at point P is 
. Determine
the gain of the amplifier,
the resistance of the resistor R.
The maximum potential produced by the microphone at point P on the figure above is 
. The power supply for the operational amplifier may be either 
or 
. State which power supply should be used. Justify your answer quantitatively.
to the inverting input.
.
. Therefore, the power supply should be 
