3a: Passive Construction

The passive voice is commonly used in academic texts for the following purposes:

• To focus on the key subject matter by putting it first or to emphasise the process/act/outcome over the doer
  
  e.g. The electric current is created by electrons or charges moving through a path called an electric circuit. An electric circuit can be formed by attaching conductors to the positive and negative sides of a power source (e.g. a battery cell).
  
  (* “The electric current” and “an electric circuit” are the key terms and concepts to be defined and described here.)


• To avoid mentioning an unknown/unclear doer or avoid attributing the action to a particular doer
  
  e.g. The electric current is classified into two types, i.e. alternating current and direct current. It is measured in ampere.


• To present information, ideas or views in a more objective tone
  
  e.g. In an experiment (which was) conducted in the Physics lesson on 3 Oct 2021, it was observed that the length and thickness of a wire would affect the current flow in an electric circuit.
  
  (c/f: In an experiment I conducted in the Physics lesson on 3 Oct 2021, I observed that the length and thickness of a wire would affect the current flow in an electric circuit.)

The passive voice is formed by a verb “to be” (in different tense forms) + past participle. e.g. The electric current is measured in ampere.