Thermal radiation from hot, dense objects produces

• A. A continuous spectrum
• B. Absorption spectrum
• C. A line spectrum
• D. A bright spectrum

Answer: (A)

Hot, dense objects emit a continuous spectrum because their thermal radiation fills all wavelengths with photons, not just specific transitions. This is blackbody behavior: at a given temperature, every wavelength is emitted to some extent, producing a smooth, uninterrupted spectrum that covers a broad range of colors. The peak shifts with temperature (Wien’s law), but the spectrum remains continuous rather than consisting of discrete lines. In contrast, line spectra come from isolated transitions in low‑density gases, and absorption spectra arise when light passes through cooler material, creating dark lines.