Types Of Light Sources Flashcards
What’s an incandescent source of light?
An object can be heated to such a high temperature that it emits visible light. This object is called an incandescent source of light. Candle flames and light bulbs can be examples of incandescent sources.
How does an incandescent light bulb glow?
Electricity heats the metal wire filament in the bulb. The filament then becomes so hot that it glows white. This energy transformation goes like this electrical energy —> thermal energy —> visible light energy.
What is a fluorescent source of light?
An example of a fluorescent source of light can be a fluorescent tube. A electrical current from the lead-in-wires and electrodes cause the mercury vapour inside the tube to give off ultraviolet radiation. A phosphor coating on the inside of the tube absorbs the ultraviolet energy and the coating then glows a light that we can see.
What are the two different energy transformations in fluorescent sources?
When standing under a black light the energy transformation goes like this:
Ultraviolet light energy —> energy absorbed by particles —> visible light energy.
When a fluorescent tube is being lit, the energy transformation goes like this:
Electrical energy —> energy absorbed by mercury particles —> ultraviolet light energy —> energy absorbed by phosphor particles —> visible light energy
What is a phosphorescent source?
A phosphorescent source is similar to a fluorescent source, except light energy is absorbed by certain particles and the energy can be stored in the phosphorescent source for a while. The energy is then released as visible light. The original light can be either high-energy UV light or visible light. The persistent emission of light following exposure to and removal of a source of radiation is known as phosphorescence.
What is the energy transformation of a phosphorescent source?
Light energy —> chemical energy —> light energy
What is a chemiluminescent source?
Light can also result in chemical reactions. The chemical reaction produces particles that give off visible light energy. This process is called chemiluminescence. Glow sticks have a breakable barrier that separates two liquids. Bending the stick causes the barrier to break and the liquids mix and cause a chemical reaction that releases light. This is an example of chemiluminescence.
What is the energy transformation of a chemiluminescent source?
Chemical energy —> visible light energy
What is a bioluminescent source?
A bioluminescent source of light relies on chemical reactions to provide energy for light. This is a special type of light produced in living creatures is called bioluminescence. It is often used by sea creatures that live deep in the ocean because not enough sunlight reaches far below the surface.
What is the energy transformation of a bioluminescent source?
Chemical energy —> visible light energy
Parts of an incandescent light bulb?
The filament and base
Parts of a fluorescent tube?
Pin, exhaust tube, mercury, phosphor coating, tube, mercury vapour, electrode, and lead-in wire
Examples of incandescence?
Stove element, light bulb, lamp, candle flame
Examples of phosphorescence?
Glow in the dark star, glow in dark clock
Examples of fluorescence?
Black light, fluorescent tube, LED light
