Although it is not wrong to use the passive voice, it can weaken the clarity of your writing. First, let's have a quick refresher on the passive. Basically, a sentence constructed inthe passive turns the object of an action into the subject of the sentence. That is, the agent performing the action is not the subject of the sentence. For example:
1. Global warming is caused byhuman activities.vs
2. Human activities cause global warming.
In a case like this one, you need to make a decision about which thing you want to emphasise, "global warming" or "humanactivities"?
A more devious use of the passive can also be to intentionally hide the agent in a sentence. For example:
The cyclist was hit on a particularly curvy stretch of road in country Victorialeaves the reader to wonder who hit the cyclist. Compare that with:
The speeding P-plater hit the cyclist on a particularly curvy stretch of road in country Victoria.
In the first example, the roadseems to be the cause of the accident, while in the second, the presumably young, inexperienced, speeding driver appears at fault.
A further example of hidden agency from use of the passive can occurincidentally by less sophisticated writers. For example:
Muslim Australians are marginalised in Australian media
begs the question of who is performing the action of marginalising others? We knowthe writer is discussing media representations, but who is doing the representing? Consider this alternative:
The editorial team for The Age marginalises Muslim Australians by limiting theirrepresentation in the paper in terms of frequency and agency.
Not only is this a specific acknowledgment of the agent of marginalisation, it forced the writer to think and write about the ways in which thepaper is marginalising Muslim Australians.
There are appropriate times to use the passive voice and you needn't be worried that you can't ever use it. You might like to use the passive to...