Everything mentioned so far is true. "Pendulum effect" is the key phrase in helping to visualize what dihedral does.

Also, if your ailerons happen to quit working while in flight, it would not make coordinated turns as well on rudder alone, if the dihedral is less. However, it would to flat turns much better. I happen to love doing flat turns, especially in front of full scale pilots that say you can't turn a plane on rudder alone.