is affect both a passive and an active verb? [duplicate]

I've noticed that some people use effect and affect interchangeably. What are the differences between these two and when are the proper situations to use each of them?

The noun is usually "effect" -- unless in more formal or literary contexts in which case "affect" as a noun can mean feeling or emotion.

The verb is generally "affect", although "effect" is possible if the meaning is "put into place" or "carry out".

Here are some example sentences:

"His plans had no effect on me."

"His disconsolate eyes brought on a sad affect."

"His plans affected me."

"He effected a plan to change the world."

The "common errors" site mentions 3 different meanings for affect (verb):

• When “affect” is accented on the final syllable (a-FECT), it is usually a verb meaning “have an influence on”:

“The million-dollar donation from the industrialist 
 did not affect my vote against the Clean Air Act.”

• “to make a display of or deliberately cultivate.”
  Occasionally a pretentious person is said to affect an artificial air of sophistication.
  Speaking with a borrowed French accent or ostentatiously wearing a large diamond ear stud might be an affectation.

• “emotion.” (when the word is accented on the first syllable (AFF-ect)).
  In this case the word is used mostly by psychiatrists and social scientists—people who normally know how to spell it.

When you affect a situation, you have an effect on it.

Less common is a verb meaning “to create” (to cause to come into being):

“I’m trying to effect a change in the way we purchase widgets.”

The Merriam-Webster details:

The verb effect goes beyond mere influence; it refers to actual achievement of a final result.

The rule that mostly works it this: affect = verb, think "a" for action, wheras effect = noun, the result of the action

to remember: "a" comes before "e" in the alphabet, and you must affect something to cause an effect