sound and light sensors

7/17/2019 Sound and Light Sensors

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SOUND AND LIGHTSENSORS

Evangelista, Fatima ElyseGranada, Paula Bianca



LIGHT SENSORS



Light

- an ultrahigh frequency Electromagnetic wave thattravels at 2.998 × 108 m/s

Wavelength ofvisible light:400 - 00 nm



Light

★Light amlitu!e is measure! in foot-can!les or lu"★Light wavelengths can #e e"resse! in $ngstroms

★%elationshi #etween frequency an! see! of light&

c - see! of lightf - frequency

wavelength



Basic terms / units

'ntensity - #rightness of light

(nit of measurement of light intensity&★English unit& foot-can!le )fc* lm/ft2

★+' unit& lu" )l"* lm/m2

★ hot )h* lm/cm2

,lumen )lm* relaces can!ela )c!* in the +' system

' - intensity - ower of source )*

% - shere ra!ius



Light Sensors

- is a !evice use! to !etect light from a source

- commonly nown as “photoelectric device” or “photo

e!or”

- converts light energy )hotons* to electricity )electrons*



Light Sensors

generate electricity !hen illuminated

Light +ensors

change its electrical "ro"erties

Photocells - use! for the !etection an! conversion oflight intensity into electrical signalslassification&

# hotovoltaic

# hotocon!uctive# hoto-emissive# semicon!uctor



Light Sensors

"hotovolt#ic cell - !evelo an E in the

resence of light

- copper oxide an! selenium



Light Sensors

"hotoco!d$ctive cell - change their resistance

when su#3ecte! to light-hotocon!uctivity results from light hitting a semicon!uctor

material which controls the current flow through it

- selenium, zirconium oxide, aluminum oxide, and

cadmium sulfide ( materials*



Light Sensors

"hoto%emiive cell - li#erate electrons in the resence of light

- release free electrons from a light sensitive material such as

cesium when struc #y a hoton of sufficient energy

- cesium oxide



Light Sensors

Semico!d$ctor &"hoto'$!ctio!( - use light tocontrol the flow of electrons an! holes across their

4-3unction

- photodiodes an! phototransistors



Light Sensors

"hoto tr#!itor - uses the level of light it !etects

to !etermine how much current can ass through the

circuit

- more sensitive than the hoto!io!e with currents are 50 to 100

times greater than that of the stan!ar! hoto!io!e



Light Sensors

"hotodiode - can turn its current flow #oth 674

an! 67 in nanosecon!s- used in cameras, light meters, CD and DVD-ROM drives, V

remote controls, scanners, fax machines and copiers



Light Sensors



Light Sources

I!c#!dece!t li)ht - ro!uce! #y electrically heating a

resistive filament: or #y the #urning of certain com#usti#le

materials

Atomic t*pe o$rce - cover gas !ischarge !evices

such as neon an! fluorescent lights

L#er emiio! % o#taine! #y e"citation of the atoms of

certain elements

Semico!d$ctor diode )LE;* - are the most

common commercially availa#le light sources use! in

in!ustry



Light Sensors Application

solar anel #ar co!e scanner security safety !evice& #urglar alarm

comuter / wireless hone / television ro#otics me!icine



SOUND SENSORS



SOUND

# Pressure !ave

# $n Physisc, $t is a vibration that "ro"agates as a ty"icallyaudible mechanical !ave of "ressure and dis"lacement,

through a medium such as air , and !ater %

# $n "hysiology and "sychology, sound is therece"tion ofsuch !aves and their "erce"tion by the brain

# &ransmitted through gases, "lasma, and li'uids aslongitudinal !aves, also called com"ression !aves

http://en.wikipedia.org/wiki/Vibration

http://en.wikipedia.org/wiki/Mechanical_wave

http://en.wikipedia.org/wiki/Pressure

http://en.wikipedia.org/wiki/Particle_displacement

http://en.wikipedia.org/wiki/Transmission_medium

http://en.wikipedia.org/wiki/Air

http://en.wikipedia.org/wiki/Water

http://en.wikipedia.org/wiki/Physiology

http://en.wikipedia.org/wiki/Psychology

http://en.wikipedia.org/wiki/Longitudinal_wave

http://en.wikipedia.org/wiki/Compression_(physical)

http://en.wikipedia.org/wiki/Compression_(physical)

http://en.wikipedia.org/wiki/Longitudinal_wave

http://en.wikipedia.org/wiki/Psychology

http://en.wikipedia.org/wiki/Physiology

http://en.wikipedia.org/wiki/Water

http://en.wikipedia.org/wiki/Air

http://en.wikipedia.org/wiki/Transmission_medium

http://en.wikipedia.org/wiki/Particle_displacement


http://en.wikipedia.org/wiki/Mechanical_wave

http://en.wikipedia.org/wiki/Vibration



SOUND A!E

# (inusoidal "lane !aves and )ongitudinal !aves



SOUND A!E

* Period + . the time bet!een successive

!aveform "ea/s* Fre'uency +in cyclessec or 1ert2 . 3"eriod,* &hus f . 3



SOUND A!E

# Wavelength of a sound is the distance travelled in one

cycle or "eriodWavelength."eriod s"eed of sound in medium +cor !avelength. c fre'uency



SOUND A!E

# 5m"litude - measure of change over a single "eriod# Pea/, Pea/-to-Pea/ and 6oot-s'uare-mean +6(7



SOUND A!E

# Soun" pressure or acoustic pressure is the local"ressure deviation from the ambient +average, ore'uilibrium atmos"heric "ressure, caused by asound !ave% $n air, sound "ressure can be measured

using a micro"hone, and in !ater !ith a hydro"hone% &he($ unit for sound "ressure p is the "ascal +symbol: Pa# Soun" pressure le#el +(P) or soun" le#el is a

logarithmic measure of the effective sound "ressure of asound relative to a reference value% $t is measured indecibels +dB above a standard reference level% &hestandard reference sound "ressure in air or other gasesis 80 9Pa, !hich is usually considered thethreshold of human hearing +at 3 /12%


http://en.wikipedia.org/wiki/Atmospheric_pressure

http://en.wikipedia.org/wiki/Sound_wave

http://en.wikipedia.org/wiki/Microphone

http://en.wikipedia.org/wiki/Hydrophone

http://en.wikipedia.org/wiki/Pascal_(unit)

http://en.wikipedia.org/wiki/Logarithmic_scale

http://en.wikipedia.org/wiki/Decibel

http://en.wikipedia.org/wiki/Micropascal

http://en.wikipedia.org/wiki/Threshold_of_human_hearing

http://en.wikipedia.org/wiki/Hertz

http://en.wikipedia.org/wiki/Hertz

http://en.wikipedia.org/wiki/Threshold_of_human_hearing

http://en.wikipedia.org/wiki/Micropascal

http://en.wikipedia.org/wiki/Decibel

http://en.wikipedia.org/wiki/Logarithmic_scale

http://en.wikipedia.org/wiki/Pascal_(unit)

http://en.wikipedia.org/wiki/Hydrophone

http://en.wikipedia.org/wiki/Microphone

http://en.wikipedia.org/wiki/Sound_wave

http://en.wikipedia.org/wiki/Atmospheric_pressure




SOUND A!E

* (ound "ressure !aves combine additively* Waves that start together are in "hase

(ounds in "hase increase in am"litude +"ositiveinterference

(ounds out of "hase cancel each other out +negativeinterference (ounds "artially out of "hase create varying am"litudes+beats



Amplitu"e scale

* (ound "ressure is measured in decibels +dB on a log30scale relative to a reference level* dB . 80 log30 P3Pr !here Pr is a reference "ressure level* 5 common reference "ressure level is the threshold of

human hearing at 3 /12, referred to as sound "ressure level+(P)* 5 sound !ith t!ice the (P) is ; dB louder

i%e% 80 log30 +8 . 80+0%< . ;



Sample soun" pressure le#els

* soft !his"er-80 dB* nearby songbird, office hum-=0 dB* bar/ing dog -0 dB* roaring lion , heavy truc/ ->0 dB

* echolocating big bro!n bat -300 dB* ?et ta/e-off-380 dB



SOUND ATTENUATION

* ("herical s"reading

* 5bsor"tion &em"erature and humidity effects* 6eflective scattering

@ue to im"edance differences



A$OUSTI$ I%&EDAN$E

&he degree to !hich a medium is com"ressibleby sound "ressure* 5coustic im"edance . s"eed of sound * densityof medium* &ransmission bet!een media !ith differentim"edances is difficult (ounds reflect off animals in air, but can "ass

through them in !ater * @ictates efficiency of sound "roduction andrece"tion by organisms



RE'LE$TION AND RE'RA$TION



RE'LE$TI!E S$ATTERING

* &y"e of scattering de"ends on ratio of !avelength andreflecting ob?ect

6ayleigh scattering +ob?ect AA !avelength* sound scattered e'ually in all directions

@iffractive or 7ie scattering +ob?ect . !avelength* both a reflected and diffracted !ave (im"le scattering +ob?ect !avelength* single reflected !ave



SOUND SENSOR

# &he main function of a sound sensor is registering sound%With most sensors you can also register the sound level%

# &he best /no!n eCam"le of a sensor that can measure

the sound level is the decibel meter, but a baby alarm canalso register the sound level% $f a baby cries too loud theDalarm in the baby intercom of the "arents !ill sound:they !ill hear their baby cry%



SOUND SENSOR

(ound sensorscalled auditory sensorsby engineersare used in many devicesthat !e use every day% &he stimulus-to-res"onse "ath!ays seen in electronicsound sensor o"eration mimics the

human body "rocess that involves ourears and signal transmission to thebrain% 7icro"hones are the soundsensors used in "hones, com"uters,baby monitors and music systems li/e/aro/e machines% &he use of sensorshas eC"loded into the design ofuncountable every day tools, e'ui"ment,a""liances and devices%



SOUND SENSOR A&&LI$ATION

# 7easure basic sound intensity

# 7easure s"eed of sound

# 7easure beats

# (tudy the do""ler effect

# onduct voice studies

# )earn musical instrument overtones



(UI)



3% )ight sensor is also commonly /no!n as HHHH



8% &his ty"e of light sensor is used in solar "anels



<% &he most common commercially available light sources

used in industry



4% )ight sensor that changes its resistance !hen sub?ected to

light%



=% What is the !avelength of light in I, if the !avelength is

4>< nmJ



;% $t is the time bet!een successive !aveform "ea/s



% (ound "ressure is measure in HHHHHHHHHHHHJ



K-30% Give < a""lication of sound sensors

sound and light sensors

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