When the cup is filled with water, the penny disappears. This happens because of refraction. When light bounces off of an object, it reaches our eyes and we see the object. As light travels through the sides of the glass and the water, it's refracted and never reaches our eyes, which makes the penny seems to disappear.
Explanation:
When the cup is filled with water, the penny disappears.
</span><span>The text, or book, of a musical dramatic work is called the libretto. </span>Libretto is derived<span> from </span>Italian and is<span> diminutive of the word </span>libro<span> which actually means "Book". The person who writes librettos is called "</span>librettist".
