How does the radiant energy from an incandescent solid differ from the radiant energy emitted by an excited gas?

incandescent solids produce a continious spectrum of radistion, excited gases - line spectrum

To understand how the radiant energy from an incandescent solid differs from the radiant energy emitted by an excited gas, let's dive into the concepts of incandescence and gas excitation.

1. Incandescence: Incandescence occurs when a solid is heated to very high temperatures, causing it to emit light. In this process, the atoms in the solid vibrate due to the increased thermal energy, causing the electrons in the atoms to move to higher energy levels. As these electrons return to their original energy levels, they release excess energy in the form of photons (light) with various wavelengths.

2. Gas Excitation: Excitation in gases happens when they are energized by an external energy source like electricity or heat. When this happens, the atoms or molecules in the gas absorb energy, causing their electrons to move to higher energy levels. As these energized electrons return to their original energy levels or transition between different energy levels, they emit photons of specific wavelengths, resulting in a characteristic emission spectrum for each gas.

Now, let's discuss the differences between the radiant energy emitted by an incandescent solid and an excited gas:

1. Continuous Spectrum vs. Line Spectrum: An incandescent solid emits a continuous spectrum of light. Since the atoms in the solid are closely packed together, their energy levels are also closely spaced, resulting in a wide range of electron transitions and thus, a continuous range of photon wavelengths. On the other hand, an excited gas emits light in the form of a line spectrum. The energy levels of gas atoms or molecules are usually more widely spaced, causing electron transitions to occur at specific energy differences and emit photons of discrete wavelengths, creating distinct lines in the spectrum.

2. Color and Intensity: The color emitted by an incandescent solid depends on its temperature. For example, a heated iron rod gradually shifts from red, to orange, to yellow as its temperature increases. The intensity of light emitted by a solid follows a continuous distribution – it is brightest at a particular wavelength and gradually decreases as you move away from that wavelength. In contrast, an excited gas emits light at specific wavelengths corresponding to the energy differences between its energy levels, resulting in a set of bright lines with varying intensities.

In summary, the main differences between the radiant energy from an incandescent solid and an excited gas lie in the nature of their spectra – a continuous spectrum for an incandescent solid and a line spectrum for an excited gas – as well as the colors and intensity patterns associated with each.