Which has more green in it, sodium vapor or mercury vapor?

Which has more green in it, sodium vapor or mercury vapor?

• A. Sodium vapor
• B. Mercury vapor
• C. Neon
• D. LED

Answer: (B)

Light color from gas-discharge sources comes from the emission lines of the gas. Sodium vapor lamps produce a single very bright line around 589 nm, which gives a strong yellow–orange glow and little green. Mercury vapor lamps emit several lines across the visible spectrum, including a distinct green line near 546 nm, so they include a noticeable green component. Neon glows red–orange, and LEDs can vary, but the green content in this comparison comes from mercury vapor. So mercury vapor has more green in its light.

Light color from gas-discharge sources comes from the emission lines of the gas. Sodium vapor lamps produce a single very bright line around 589 nm, which gives a strong yellow–orange glow and little green. Mercury vapor lamps emit several lines across the visible spectrum, including a distinct green line near 546 nm, so they include a noticeable green component. Neon glows red–orange, and LEDs can vary, but the green content in this comparison comes from mercury vapor. So mercury vapor has more green in its light.