Final answer:
Temporary fixtures in theater are used to enhance the primary light source and create a realistic scene.
Step-by-step explanation:
In theater, temporary fixtures are used mainly to create a realistic scene and enhance the primary light source. For example, if a scene requires only a table lamp as the light source, a lighting designer may use additional theatrical fixtures to provide key and fill lights without making them visible to the audience. This technique allows the audience to focus on the actors and creates an immersive experience.