The following, provided by Paul Carlin, CA OES Coastal Region ACS Officer, is important to both managers and participants.
Coercive power is based primarily on fear.
Here, person A has power over person B because A can administer some form of punishment to B, such as firing him. Reward power exists when person A controls rewards that person B wants. This may be salary, promotion, bonuses, etc. Legitimate power exists when person B submits to person A because he feels A has a right to exert power in a certain domain. A supervisor has a right, for instance, to assign work.