Sometimes active and passive voices are confused with past and present tense. But changing a sentence from passive or active voice does not mean changing the tense of a verb; the action will still occur at the same moment in time. Instead, the order of the doer and the receiver for the action is changed, and a "to be" verb is additionally added or taken out.

With active voice, the subject is directly performing the action. For example:

Johnny plays the guitar.

Using passive voice means making the object receive the action and typically adding a form of "to be." For example:

The guitar is played by Johnny.

" Is " is the "to be" verb that was added, which is still present tense as in the first example. The preposition " by " was also added to signify that Johnny is the doer of the action, " plays ."

• ask yourself: what are the subject + verb + object
  (in other words..) WHO did WHAT to WHOM?

• Passive Voice: Scientific writing uses passive voice more often than other discourses, although it is certainly not just limited to lab reports. Passive voice makes sense when the subject performing the action is obvious, unimportant, or unknown. A writer may also use passive voice if they are purposefully trying to postpone or avoid mentioning the subject. The passive voice is effective in such circumstances because it highlights the action and what is acted upon, rather than who or what is performing the action.
• Active Voice: Although passive voice works well in many forms of scientific writing, active voice is generally preferred over passive voice for most other types of writing. Overuse of passive voice in an essay or the use of passive voice in long and complicated sentences can cause readers to lose interest or to become confused. Sentences in active voice are generally clearer and more direct than those in passive voice.

• Example 1:
  • Passive Voice: A batch of cookies was made by my sister yesterday.
  • Active Voice: My sister made a batch of cookies yesterday.
• Example 2:
  • Passive Voice: The bus fare will be raised to $1.50 next week by the city council.
  • Active Voice: The city council will raise the bus fare to $1.50 next week.
    (OR) Next week, the city council will raise the bus fare to $1.50.
• Example 3:
  • Passive Voice: The bumper of the car was dented. (*note- subject unknown)
  • Active Voice: Jill dented the bumper of the car.
• Example 4:
• Passive Voice: The dog is being chased by the little boy in the park.
• Active Voice: The little boy is chasing the dog in the park.
• Example 5:
• Passive Voice: Sometimes active and passive voices are confused with past and present tense. (*note-subject unknown)
• Active Voice: Students sometimes confuse active and passive voices with past and present tense.
  

Hansard, Michelle. "OWL Online Writing Lab: Passive and Active Voice." Purdue University Online Writing Lab, Dept. of English, Purdue University . 9 Apr. 2008 <http://owl.english.purdue.edu/handouts/grammar/g_actpass.html>.

"The Writing Center : Active vs. Passive Voice." LAVC Writing Center , Los Angeles Valley College . 9 Apr. 2008 <http://www.lavc.cc.ca.us/WCweb/activepassive.html>.