In "The Tell-Tale Heart", how is imagery used to create tension? What images are used repeatedly, creating striking descriptions that affect the...

There are a couple great images-and sounds-that increase the tension of the text.  The first is the descriptions of the old man's eye, which is the catlyst for the murder:  "He had the eye of a vulture—a pale blue eye, with a film over it. Whenever it fell upon me, my blood ran cold." and then later, "all a dull blue, with a hideous veil over it that chilled the very marrow in my bones."  It is a great description; the reader can certainly feel the creepiness of the eye, and the accompanying horror in the blood.  Then, in the first half, you have repeated descriptions of the narrator's cautious, steady, silent stalking and waiting.  That alone is tense; we keep waiting for him to slip, to make a noise, to be discovered.  The most effective repeated imagery (5 senses, not just sight) is that of the heartbeat, which starts off as "a low, dull, quick sound, such as a watch makes when enveloped in cotton," increases to a "hellish tattoo", and keeps getting "louder, louder!".  The sound of the heartbeat increases the tension just as a movie soundtrack would, and leads to the murder and confession.

Poe uses images and imagery to help the reader feel like they are actually there, experiencing the situations and emotions, and it makes for a really great story.