A person who assumes to act as an agent is responsible to third persons as a principal for acts in the course of the agency in any of the following cases and in no other:
(1) when, with the agent's consent, credit is given to the agent personally in a transaction;
(2) when the agent enters into a written contract in the name of the principal without believing in good faith that the agent has authority to do so; or
(3) when the agent's acts are wrongful in their nature.