I use a spectrometer to measure the optical spectrum of ligh

I use a spectrometer to measure the optical spectrum of light emitted from a variety of light sources such as from incandescent lamps, fluorescent lamps, light-emitting diodes and laser diodes. And below is the data and the graph.please comment on the characteristics of each type of light source

35000 ncandescent Lamp Fluorescent lamp 30000 _LED 25000 Laser Diode 20000 15000 10000 5000 400 450 500 550 600 650 700

Solution

Answer:

Incandescent Lamp:

An incandescent light bulb contains a tungsten filament that is resistively heated when a current is conducted through it. At temperatures around 2000 K, the filament starts to emit visible light. To prevent the tungsten wire from burning up, the bulb is filled with a gas, usually argon. The heat generated in the filament is transported to the surroundings through radiation, convection, and conduction. An incandescent bulb emits a greater proportion of red light (As we can see Intensity getting higher at 650 - 700 nm for red wavelength region) than natural daylight. Emission even extends into the infrared part of the electromagnetic spectrum, which wastes energy and reduces the overall efficiency of the bulb.

Fluoroscent Lamp:

A fluorescent lamp typically consists of a long, glass tube containing a low-pressure mixture of mercury and a rare gas, such as argon. Inside of this tube, a nonequilibrium discharge is produced (a plasma). This means that the electron temperature is different from the temperature of the surrounding gas mixture. For example, the electron temperature can be on the order of over 20,000 K, but the gas temperature stays relatively close to room temperature, 300 K. Since the plasma is not in equilibrium, the electron impact reactions modify the chemical composition of the gas mixture in a manner governed by the collisional processes. These collisions can produce electronically excited neutrals, which can subsequently produce spontaneous emission of photons at specific wavelengths. Like incandescent bulbs, fluorescent bulbs can be inefficient because the plasma needs to be sustained and it emits radiation in the nonvisible range. We can also see the quantization of energy (sharp peak with continous spectrum) in the spectrum and they can also cause inefficiecy if they lie non visible region.

LED Lamp:

LEDs are so much more efficient than incandescent bulbs because they function in a very different way. LEDs are semiconductor devices that emit light when electrons in the conduction band transition across the bandgap via radiative recombination with holes in the valence band. Unlike incandescent bulbs, LEDs emit light over a very narrow range of wavelengths. LED light bulbs operate at 10-20% of the power needed to run an incandescent bulb of comparable brightness and they also have very high durability. LEDs are revolutionizing the lighting industry, as they are often much more efficient in terms of the luminous efficacy and more durable than traditional incandescent light technologies. It may be noted that here light is generated by diffrent process than to incadescent and fluoroscent lamp. Still the light we get is white to our eyes.

Laser Lamp:

We can see the quantization of energy at a particular wavelength and its multiple. We get a color of that particular wavelength from the laser light.