Incandescent light bulbs contain a metallic filament inside. Metallic systems have allowed energy levels in a continuous range of energy, so electrons can make transitions of any energy within that range. In our lab, we will connect a light bulb to a variable AC voltage source (a Variac), which can deliver 0-140 V to the filament. The higher the voltage, the hotter we make the temperature, and the more energy we are giving the electrons in the metal, Suppose that at 20 V the filament is a dull red color, which means that most of the photons being emitted are red. When we increase the voltage, what color of light do you expect the filament to emit?