In my opinion, any plot is possible only if you have the set of values in order. If there are 10 x values, then you must have a corresponding 10 y values. If y is the function of x as a variable in it, then, the above condition is satisfied and it is possible to plot x vs y. If there is another function say x1 which is a function of x, then again the above condition is satisfied and you can plot x1 vs y.
It goes on and in this way, you can plot y vs x1*x2 (i.e. the product of x1 and x2). In the query, it is difficult to get such relation among V(r), E0 and B0.
Assuming all the are functions of say a variable r, then find V(r), E0(r) and B0(r) for say 5 values of r (=0.1, 10,100,1000,10000 just like that I gave, it can be like 1,2,3,4, and 5 as well). For example, E(r) = r, B0(r) = r*r, and E0(r) = 3r and r = 1,3,5,7,8 and 9.
Then V = [1, 3, 5, 7, 8, 9]; B0 = [ 1, 9, 25, 49, 64] and E0 = [ 3, 9, 15, 24, 27].
Then only it is easy for anyone (software) to plot using plot command plot(E0, V) or plot(E0*B0, V).Hope this helps in making your plot easily possible.Ramakrishnan V