Ohm's law as a formula is V=IR.So, R=V/I.So, if the R remains constant, then the as the voltage is increased, so will be the current, in proportion.On a graph, that should show as a straight line if, say, V were plotted horizontally, and I vertically. (It's probably easier to change a voltage than it is to change a current, so V would be the independent variable and I would be the dependent variable. The resistance would then be the reciprocal of the slope.
