Your friend, who is not in a physics course, is looking at your notes over the single-slit interference experiment and asks: Why does the vertical slit produce a horizontal interference fringe? Why does the horizontal slit produce a vertical interference fringe? Is this magic? How would you answer this question? Use the concepts we have been working with in physics up to this point to explain your answer.

Your friend, who is not in a physics course, is looking at your notes over the single-slit interference experiment and asks: Why does the vertical slit produce a horizontal interference fringe? Why does the horizontal slit produce a vertical interference fringe? Is this magic? How would you answer this question? Use the concepts we have been working with in physics up to this point to explain your answer.