In a negative feedback amplifier using voltage-series (i.e. voltage-sampling, series mixing) feedback.
- $R_i$ decreases and $R_0$ decreases
- $R_i$ decreases and $R_0$ increases
- $R_i$ increases and $R_0$ decreases
- $R_i$ increases and $R_0$ increases
($R_i$ and $R_o$ denote the input and output resistances respectively)