Graphite is an electric conductor, consequently, useful in such applications as arc lamp electrodes. It can conduct electricity due to the vast electron delocalization within the carbon layers (a phenomenon called aromaticity). These valence electrons are free to move, so are able to conduct electricity.
A beer bottle is a bottle made to contain beer, usually made of glass and comes in various sizes, shapes, and colors (usually brown or green). Dark amber or brown glass greatly reduces the presence of UV light, a contributing factor of beer spoilage. However, lighter-colored bottles are often used for marketing reasons.