Does an HMI lamp have a filament?

• A. Yes
• B. No
• C. Only in Older Models
• D. Only for Low Wattage

Answer: (B)

HMI lamps operate as high-intensity discharge lamps, producing light from an electric arc inside a quartz tube filled with mercury and metal halide vapors. The arc forms between two electrodes at the ends, not by heating a filament. A ballast provides the high starting voltage and then regulates current to sustain the arc. Since the light comes from the arc discharge rather than a heated filament, there is no filament in an HMI lamp. This is why the correct answer is no. Filament-based light is characteristic of incandescent lamps, not HID lamps like HMI.