Voice is one of the essential parts of English grammar. There are two main types of voices: Active Voice and Passive Voice. When the subject performs a particular action, it is called active voice. When the subject receives a specific action, it is called passive voice. 

Example: 

He likes cake. (Active Voice)

Cake is liked by him. (Passive Voice)

The structure of the sentence in the active and passive voice

• In the case of an active voice, the subject is a performer of a particular action.

             Form: Subject + Verb + Object

• Intelligent passive voice the certain action is performed by the sentence’s subject.

Form: Object + Verb + Subject

Way to differentiate between active and passive voice

Active and passive voice can be differentiated from each other by asking the following questions

• What/who is doing a certain task?
• Which is the verb of the sentence?
• Is the subject of the sentence doing any action?

When the last question’s answer is Yes, then the sentence is to be considered in an active voice. The sentence is regarded as the passive voice when the answer is no.

Changes in the auxiliary verb

When the form of the main verb changes. In that case, the tenses of the auxiliary verb change as well. 

Active and passive voice in accordance with sentences

Conversion of active voice into passive voice

1. Present simple tense

Form in passive voice: Object + is/am/are + Verb (3rd form) + by + subject

For example: 

Active voice: He bakes a cake.

Passive voice: A cake is baked by him.

2. Past simple tense

Form in the passive voice: object + was/were + Verb (3rd form) + by + subject

For example: 

Active voice: I loved my dog.

Passive voice: My dog was loved by me.

3. Future Simple tense

Form in passive voice: object + will/shall + be + Verb (3rd form) + by + object

Active voice: We will buy a car.

Passive voice: A car will be brought by us.

4. Present Continuous Tense

Form in passive voice: Object + is/am/are + being + Verb (3rd form) + by + subject

For example: 

Active voice: I am writing a book.

Passive voice: A book is being written by me.

5. Past continuous tense

Form: Object + was/were + being + Verb (3rd form) + by + subject

Example: 

Active Voice: She was writing a letter.

Passive Voice: A letter was being written by her.

6. Present Perfect Tense

Form: Object + has/have + been + verb (3rd form) + by + subject

Example: 

Active voice: He has finished his homework.

Passive Voice: His work has been finished by him.

7. Past perfect tense

Form: Object + have + been + Verb (3rd form) + by + subject

Example: 

Active voice: They had completed the work. 

Passive voice: The work had been completed by them.

8. Future perfect Tense

Form: Object + shall/will + have + have been + verb (3rd form) + by + subject 

Example: 

Active voice: You will have completed the task.

Passive voice: The task will have been completed by you.

Important points to keep in mind:

• Future continuous and perfect continuous tenses cannot be converted into passive voice.
• The verb of the words like be, seem, have cannot be converted into passive voice.

Rules for active and passive voice: 

• The object of the verb in the active voice becomes the subject of the sentence in passive voice.
• It is important to use the third form of the verb with the passive voice, as passive uses past participle form. Example: The race was won by her. Here, won is the third form of the verb win.
• An auxiliary verb ‘be’ can be added with the (is/am/are/was/were). Just before the past participle by, keeping a look on the tense of voice.
• Usually, the word by ‘by’ is added just before the object of passive voice sentences
• When some case is being discussed, you can change the subject of passive voice. This task is to be done based on your judgment.
• Some words can only be transferred in passive voice by using fixed prepositions. Can be: tired off, filled with, decorated with, amazed by.

Conclusion

The term voice can be defined as the form of a verb indicating action. There are two types of voices: active voice and passive voice. When a subject performs a specific action, it is an active voice. When the subject is acted upon, it is called a passive voice.  One must be thorough with the rules of active voice and passive voice to write them correctly.