Effects of Word Choice in Narrative

Read the following excerpt from a fictional narrative:

"As the storm raged outside, the flickering candle cast long shadows on the walls. In the eerie silence that followed each crack of thunder, Sarah could feel her heart racing with a mix of fear and excitement. It was as if the tempest outside mirrored the chaos within her thoughts—each crack and boom echoing the confusion she felt about her future. Would she ever find the courage to pursue her dreams? Or would the anxieties of the world keep her bound to her mundane existence?"

In the sentence 'the flickering candle cast long shadows on the walls,' what is the primary effect of the word choice in the phrase 'flickering candle'?