I want to plot the following function.
f(r) = 1 - $\frac{10}{r}$ e$^{-\frac{0.7^2}{10 r}}$.
I can specify x-axis range using
Plot[f[r],{r,0,20}]
For the above input, in the output, mathematica is showing a plot in which y axis range is from 1 to -5, with step size of 1. I want y axis range from 1 to -30 with step size of 5. How to do that ?