Sources Of Light Flashcards
What are the sources of light?
-natural and artificial
-light can come as hot objects turn VERY hot and emit white light(sun,light bulbs)
-fusion reaction of sun create enormous amounts of heat and light
Luminous vs non luminous
And examples
Emit light=luminous
-screens
-fireplace
-candle
-stove
Don’t emit light =non luminous
What is incandescence light?
-light that is emitted by a vary hot object
-most common source for humans
-Light bulbs heat up because electrons can’t go through
-OG light bulbs are inefficient at producing light because most of the energy goes to heat
What is light from electric discharge?
-light that is emitted from a heated gas or vapour
Ex:neon lights
What is Luminescence and the three types?
Light that is generated without heating something
1.phosphorescense
-absorbs energy and releases it back over a long period of time
-glow-in-dark
2.chemiluminescence
-light from a chemical reaction
-glow sticks
3.Bioluminesecense
-light from living things
-fire flies (lightning beetles)
What is fluorescence?
-light that is emitted during exposure of source to UV light
-can put that compound in anything
-many body fluids and molecules are fluorescent so UV lights can be used at crime scenes
-20$ bills
Ex:fluorescence lights
What are the three effect of materials on light?
- Opaque material-absorbs light (doesn’t let it go through)
- Transparent materials-allows light to easily pass through them
3.Translucent materials - allows light to pass through but distorts the light during the passage
What is the electromagnetic spectrum?
-they travel in waves
-A wave is electromagnetic, two waves electric and magnetic wave
- all waves are slightly different
-when you set a radio you set the specific wave lengths
What are radio waves?
-have longest wavelengths and lowest frequencies of all the electromagnetic waves
-travel long distances
What is and MRI?
Uses radio waves with a magnet to create and image
What is a Microwave?
-considered radio waves but short ones
- shorter wavelengths and higher frequency than radio waves
-range from 1m to 1mm
-wireless communication
Ex. TV, garage open automatic
What is Infrared?
-we can’t see
-below red
-you can feel the longest ones as warmth on skin
-heat lamps give off infrared waves
What is Thermogram?
-people give off infrared radiation
-detects heat emitted from objects
What is Visible light?
-electromagnetic waves we can see
- longest wave length is red
-shortest wavelength is violet
What is Ultraviolet (UV)?
-shortest wavelength and higher frequency than visible light
-carry more energy than light
-used to kill bacteria
-causes skin to produce vitamin D
-too much=skin cancer
What are X-Ray?
-shorter wavelength and higher frequency than UV
-can’t pass through matter like tissues
-bone and teeth absorb x-rays
-can penetrate most matter
-part of an x-ray image indicates a place where the x-ray was absorbed
-used by engineers to check for thing cracks in structures
What are Gemma rays?
-shorter wavelength and higher frequency than x-rays
-carry the greatest amount of energy and penetrate the most
-used in radiation treatment to kill cancer cells
- can be harmful if not used correctly
