The active and passive voices have appropriate uses and settings, and using them appropriately will make your writing more effective.
Use active voice in concise, non-scientific writing, like newspapers or in the humanities. Active voice helps to emphasize WHO did the action, rather than what the action was.
Passive voice is often used in scientific writing because it emphasizes WHAT was done, not who did it. It is also used to de-emphasize the “who,” especially when the “who” is unclear or unimportant.
Emphasize the ACTOR or OBJECT
The active voice assigns more responsibility to the actor. The passive voice will shift the focus away from the actor if he/she does not want to be responsible or if it is not needed.
Actor: the “who” of the sentence
Verb: the “action” of the sentence
Object: the “what” of the sentence
Active: More than half of the athletes passed their challenging classes.
Passive: The challenging classes were passed by more than half of the athletes.
Active: BP spilled 210 million gallons of oil in 2010.
Passive: 210 million gallons of oil were spilled in 2010.
Active: Dr. Jones delivered baby Emily today.
Passive: Baby Emily was delivered today.
Keep it CONCISE
The active voice generally makes a sentence shorter and to the point. The passive voice will make a sentence longer and wordier.
Active: The dog bit me.
Passive: I was bitten by the dog.
Active: The student uses many unnecessary words.
Passive: A lot of unnecessary words have been used by the student.