How do HID Light Bulbs Work

HOW A HID LIGHT BULB WORKS 

1. An electrical charge is released from the ballast. The ballast is not part of the HID of lamp. 
2. The cathodes release chemical materials to trigger the electric arc.
3. The electric arc is released a d begins to pass between the cathodes. 
4. Mercury and other gases inside of the lamp reach an excited state producing radiant energy also known as UV light.
5. The UV light strikes the inner walls of the lamp which are covered in phosphor, which converts the energy to visible light.

 *The type of phosphor coating determines the color of light emitted from the lamp.