chapter 12 section 3
fluorescent lights use ___ of the electrical energy to produce the same amount of light as incandescent lights
1/5
what percent of thermal energy is given off by an incandescent light bulb and how does that relate to efficiency?
90 % very inefficient
how is light amplified in a laser?
as the light waves bounce back and forth between the mirrors in the laser they stimulate other atoms to emit more light waves
how do the atoms in a laser emit their excess energy?
by emitting light waves of a certain wavelength
light of only one wavelength that travels in one direction with a constant distance between the corresponding crests of the waves
coherent light
light waves can be ___ or ___
coherent, incoherent
name 5 reasons fluorescent lights are more economical than incandescent lights
cost less, more efficient, last longer, release less fossil fuels used to produce electricity, decrease amount of carbon dioxide and pollutants released into atmosphere
when there is an electric current in the filament, the ___ of the metal causes the filament to become hot enough to give off light.
electric resistance
the reflected light is then converted to an ___ that can be converted to sound or images
electric signal
an ___ is at the end of a fluorescent bulb
electrode
t/f when the light waves are emitted from the atoms they all stay in the tube
false most of the light waves travel out of the tube
inside an incandescent light bulb is a small coil of wire, called a ___, that is usually made of ___
filament, tungsten metal
light generated by using phosphors to convert ultraviolet radiation to visible light.
fluorescent light
the wavelength of light emitted from the fluorescent bulb depends on the type of ___ used
gas
lights that contain a mixture of neon gas, a small amount of argon gas, and a small amount of sodium metal. when the lamp is turned on, the gas mixture becomes hot and causes the sodium metal to vapor. this emits an orange yellow glow
sodium vapor lights
t/f lasers can be made with many different materials such as liquids, gases, solids
true
describe the set up of a helium neon laser
tube filled with mixture of helium and neon gases and mirrors at both ends
____ are sometimes used to create intensely bright light.
tungsten halogen
these lights have a tungsten filament inside a quartz bulb or tube. the tube is filled with a gas that contains one of the halogen elements ( fluorine, chlorine) which enables the filament to become much hotter than one in an incandescent bulb and as a result causes the light to be much brighter
tungsten halogen lights
the electrons collide with gas atoms which then emits____
ultraviolet radiation
the ___ of the laser depends on the material used
wavelength
coherent waves combine to form a wave with constant ___ and ___
wavelength, frequency
when are electrons given off in a fluorescent bulb?
when the electrodes are connected in a circuit
identify two ways of producing light.
heating a filament, passing a current through a gas
where might incandescent lighting be used?
home
light generated by heating a piece of metal until it glows
incandescent light
light that can have more than one wavelength that can travel in more than one direction, and does not travel with a constant distance between the corresponding crests of the waves
incoherent light
what type of light is spread out over a large area and why?
incoherent light because the waves do not travel in the same direction
lasers can be used in ___, ___ ,___ and ___
industry, medicine, building and communications
the pits on the bottom of a disc store ___
information
a laser is also used to ___ the disc
read
the most common type of laser is the helium - neon laser which emits __ light
red
what color light is emitted when electrons collide with neon gas?
red
identify source of incoherent light
regular lightbulb, flashlight
lasers can be used in place of ___ in medicine
scalpels
where might fluorescent lighting be used?
schools, offices, hospitals, factories
____ are often used for streetlights and other outdoor lighting
sodium vapor lights
when a disc is produced, the information is burned into the disc with a ___
laser
identify a type of coherent light
laser light
identify three tools that can apply large amounts of energy in small places
lasers, videodisc players, surgical tools
name two advantages of tungsten halogen bulbs and one disadvantage
last longer, glow brighter, can cause fires because of the amount of thermal energy that they produce
as the laser beam strikes the disc different amounts of light are reflected to a ___
light sensor
a fluorescent bulb is filled with ... and coated inside with ..
low pressure gas, phosphors
name four places tungsten halogen bulbs are used
movie sets, car headlights, underwater photography, baseball stadium
lasers produce ___, ____ beams of light in a single direction
narrow, intense
lighting devices that work similarly to fluorescent lights but are filled with neon gas and are used for eye catching signs
neon lights
identify what causes the color in a neon light
neon lights emit a bright red orange because the electrons collide with neon gas and emit visible light
name the three conditions of light in coherent light
one wavelength traveling in one direction with a constant distance between corresponding crests
substance that absorbs ultraviolet radiation and then emits visible light
phosphor
what is the final step in producing light in a fluorescent bulb?
phosphors absorb the ultraviolet radiation and convert it to visible light
the atoms in the laser then absorb ___ energy from a flashtube
radiant