The effective potential is the sum of two terms: the ordinary potential, $$-\frac{k}{r}$$ for spherically symmetric gravitational or electrostatic forces; and the angular part of the kinetic energy, $$-\frac{\ell^2}{2\mu r^2}\text{.}$$
The applet below shows you how the effective potential depends on the parameters: (magnitude of the) angular momentum $$\ell\text{,}$$ strength of the force $$k\text{,}$$ and reduced mass $$\mu\text{.}$$ (Note that the dependence of $$k$$ on $$\mu$$ for the case of gravitational forces has been ignored.)
Explore how the shape of the effective potential (shown in black) depends on the parameters $$\ell\text{,}$$ $$k\text{,}$$ and $$\mu\text{.}$$