Answer:
The purpose of the porter scene is to create a heavy atmosphere and to herald the betrayal Macbeth will do to King Duncan.
Step-by-step explanation:
This question is about Macbeth. Where the porter scene refers to the moment when he makes a joke about him he is guarding the gates of hell. This may serve to give a certain relief to me with the scenes that will follow, but it is also a subjunctive way of foreshadowing the homicide that will be established, in addition to creating a heavy atmosphere in the work. The porter also says that he is opening the gates for the soldiers who "carousing till the second c**k" this alludes to the c**k that sang when Peter denied and betrayed Christ three times, foreshadowing the betrayal that Macbeth would do to King Duncan.