Describe the spectrum of the light from a fluorescent lamp and from an incandescent (tungsten filament) lamp, and try to explain what you observe.
So fluorescent lamps use electricity to excite mercury vapour, and the excited atoms produce short-wave UV light which causes a phosphor (from the phosphorescent coating) to fluoresce, producing visible light.
Incandescent light bulbs use electric current to flow through a tungsten wire which gets heated to the point where it begins to emit thermal radiation.. but I'm not exactly sure how this gets transmitted into visible light?
Can someone please help me out with these explanations? Maybe explain the specific emission spectra of each type of light and why it produces the light it does? I'm confused. And the explanations online are getting really complex
The fluorescent light sounds good to me. You started the W light great, too, but tailed off. The W wire is heated to incandescence (hence the name?) and it emits what appears to be white light if one looks at it; however, it is a continuous spectrum running from very little in the violet, more in the green and red and a rather large amount of infrared radiation. It is visible light because the W wire glows so brightly it actually is visible light. Look at a W bulb and you will see how bright it is. I suggest a small wattage bulb. I have some night lights in my bathroom that are 4 watts and you can see the glow and the color.
Fluorescent lamps and incandescent lamps both produce light, but the mechanisms behind their light production are different, resulting in different spectral characteristics.
Fluorescent lamps generate light through a process called fluorescence. This type of lamp contains mercury vapor, which is excited by electricity passing through it. When this happens, the excited mercury atoms emit ultraviolet (UV) radiation, which is not visible to the human eye.
To convert the UV radiation into visible light, a phosphorescent coating is applied on the inner surface of the lamp. This coating absorbs the UV radiation and re-emits it as visible light. The specific composition of the phosphor coating determines the color of the light produced. Multiple phosphors can be used to achieve a wider spectral output.
The spectrum of a fluorescent lamp typically consists of several distinct lines, corresponding to the different phosphors used and the specific energy levels of the excited mercury atoms. However, the overall distribution of the emitted light is relatively smooth and covers a wide range of visible wavelengths.
On the other hand, incandescent lamps rely on the principle of thermal radiation. Inside an incandescent bulb, an electric current passes through a tungsten filament, heating it to a very high temperature. As an object is heated, it emits thermal radiation, also known as blackbody radiation.
The spectrum of an incandescent lamp follows a distribution known as a blackbody spectrum. This distribution is continuous and shows a peak at a specific wavelength, which depends on the temperature of the filament. In the case of tungsten filament lamps, the peak is in the infrared range, but a significant portion of visible light is also emitted.
Incandescent lamps emit a broad spectrum of light, including all visible wavelengths, which gives them a warm and natural appearance. However, a relatively high portion of the energy is emitted as heat, making them less energy-efficient compared to fluorescent lamps.
In summary, fluorescent lamps produce light through the excitation of mercury atoms and subsequent conversion of UV radiation into visible light by phosphors. This results in a broad, smooth spectrum with distinct lines. Incandescent lamps, on the other hand, rely on heating a tungsten filament to emit thermal radiation, which produces a continuous spectrum peaked in the infrared range but with a significant portion of visible light as well.
Certainly! Let's start with the spectrum of light emitted by a fluorescent lamp.
Fluorescent lamps produce light through a two-step process. First, electricity is used to excite the mercury vapor inside the lamp, causing the mercury atoms to become energized. These excited atoms then release their energy in the form of ultraviolet (UV) light. However, the ultraviolet light is not directly visible to the human eye.
To convert this ultraviolet light into visible light, fluorescent lamps are coated with a layer of phosphor, a substance that can absorb the high-energy UV light and re-emit it as visible light. The phosphor coating is designed to emit light at specific wavelengths, depending on the composition of the phosphor material used.
The spectrum of light emitted by a fluorescent lamp consists of several distinct lines or bands, each corresponding to a different wavelength of light. The specific spectrum depends on the type of phosphor coating used and can vary between different models or brands of fluorescent lamps.
Now let's move on to the spectrum of light emitted by an incandescent lamp, which uses a tungsten filament.
Inside an incandescent bulb, electric current passes through a tungsten wire filament. As the current flows, it causes the filament to heat up to several thousand degrees Celsius. When an object reaches such a high temperature, it emits thermal radiation, which includes a wide range of wavelengths, including infrared, visible, and even some ultraviolet light.
The thermal radiation emitted by the tungsten filament is referred to as incandescence. However, a significant portion of the total radiation emitted is in the infrared range, which is not visible to the human eye.
The spectrum of light emitted by an incandescent lamp consists of a continuous distribution of wavelengths, ranging from the infrared to the visible spectrum, but with a peak in the visible range. The specific shape of the spectrum depends on the temperature of the filament. Incandescent lamps have a warmer, reddish light compared to the cooler and more bluish light of fluorescent lamps.
In summary, fluorescent lamps produce light by exciting mercury vapor and using phosphor to convert the resulting UV light into visible light. The resulting spectrum typically consists of specific lines or bands, depending on the phosphor coating. On the other hand, incandescent lamps produce light through the heating of a tungsten filament, resulting in a continuous spectrum of light with a peak in the visible range.