Which is a continuum light source?

Which is a continuum light source?

• A. Mercury vapor lamp
• B. Hollow cathode lamp
• C. Deuterium lamp
• D. Mercury-sodium vapor lamp

Answer: (C)

A continuum light source emits light over a broad, essentially uninterrupted range of wavelengths rather than discrete lines. The deuterium lamp fits this description because it produces a wide, continuous spectrum in the ultraviolet region (roughly 160–400 nm), providing a smooth baseline for UV measurements. In contrast, mercury vapor, hollow cathode, and mercury-sodium vapor lamps each emit light at specific wavelengths as sharp spectral lines, not a smooth continuum. These line emissions arise from atomic transitions in the elements present and are used when precise lines are needed. Thus, the deuterium lamp is the continuum source.

A continuum light source emits light over a broad, essentially uninterrupted range of wavelengths rather than discrete lines. The deuterium lamp fits this description because it produces a wide, continuous spectrum in the ultraviolet region (roughly 160–400 nm), providing a smooth baseline for UV measurements. In contrast, mercury vapor, hollow cathode, and mercury-sodium vapor lamps each emit light at specific wavelengths as sharp spectral lines, not a smooth continuum. These line emissions arise from atomic transitions in the elements present and are used when precise lines are needed. Thus, the deuterium lamp is the continuum source.