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