A student measures the terminal potential difference ($V$) of a cell (of emf $ϵ$ and internal resistance $r$) as a function of the current ($I$) flowing through it. The slope and intercept of the graph between $V$ and $I$ are respectively:

The relationship between terminal potential difference ($V$), emf ($ϵ$), and internal resistance ($r$) for a discharging cell is:
$$V=ϵ-Ir$$
Rewriting this in the form of a straight line equation ($y=mx+c$):
$$V=(-r)I+ϵ$$
Comparing the terms:The variable on the y-axis is $V$.The variable on the x-axis is $I$.The slope ($m$) is $-r$.The y-intercept ($c$) is $ϵ$.