Intensity Diode

physics laboratory: polarization-- Malus' Law?

i would like to ask if the graphs i did for our laboratory activity is correct.

these are graphs made from data collected for a laboratory activity in physics (elementary optics and electromagnetism).

graph 1: intensity versus angle for the laser diode polarization setup

http://i337.photobucket.com/albums/n363/binibiningarki06/intensityversusangleforthelaserdiod.jpg

graph 2: intensity versus angle for the plain light source

http://i337.photobucket.com/albums/n363/binibiningarki06/intensityversusangleforplainlightso.jpg

More questions:
Is malus' law obeyed by these graphs? How can i qualify my answer?
Does the intensity of the light source determine whether Malus' Law is obeyed or not? How is this supported by the plot?

for both graphs 1&2,
on blue: true intensity versus angle
on violet: theoretical intensity versus angle

I think it would certainly help if you mentioned what the two colors are in each graph. My guess is that the dark line is the intensity vs angle -- I have no idea what the light line might be.

Malus's law says that intensity goes as cos squared of the angle between E field and polarizer.

If you plot cosine squared, you will see that it starts at the maximum, goes to the minimum at 90 degrees, then goes to a max at 180 again. Your first graph certainly shows this effect. Qualitatively, you could plot 350 * cos(theta) * cos(theta) onto your graph, and show that it has the same form. Quantitatively, you would fit the curve exactly (nonlinear least squares fit), then report the residual error.

The second curve, plain light source, does show some effect. That surprises me -- were you using two polarizers? Again, plot a cos^2 with a reasonable amplitude (1.8?) to see how it compares. Since your signal is much lower, you'd expect more noise in this case.

The intensity of the source plays no real part to whether malus's law is obeyed -- although does play a part in your ability to measure it accurately. For instance, you have to start worrying about room ambient lights. Also, the divergence angle of the beam certainly plays a role, as your polarizer probably has some dependance on angle of incidence. Also wavelength band of your source may play a role.

Intensity $9.73 Intensity

DIODE $12.5 When these electrical items fail there is little choice but to renew - With this genuine Suzuki par..

Transistor-Diode Checker Kit $4.95 Transistor-Diode Checker Kit

Mackin Diode Light Pen, Pearl $10 Features of the Mackin Diode Light Pen: A quality pen with a diode flashlight.

Diode City $7.98 The 1998 record Diode City, the third for Japanese rockers Supersnazz, presents a change for the band. Not only is the once all-girl group now a girl group with male drummer -- Shoe, who formerly did drumming duties for Teengenerate has replaced Skinny Minny -- but this is a more poppy and playful album than their 1993 debut Superstupid!, with a cleaner sound and vocals, and lyrics that are more comprehensible. The band has also improved as songwriters and musicians, crafting songs for this album that have more layers of texture and greater complexity. But while it's hard to fault a band for getting better, some of their former tough energy is lost, like a street punk who learns to fight and doesn't need to hide behind his sneer anymore because he knows he can hold his own now. The band still takes the innocence and sound of American rock & roll from the 1950s and '60s as their foundation, and energizes with their own dose of pop-punk attitude. The album opens with "Words of Love," a sappy but infectious love song like those from the American Bandstand days, whose catchy rhythm ricochets into a fiery guitar solo. Kanako's guitar has a cool, slinky spy theme sound in "Diode City" and a surf flavor on "Tell No Tale." Their cover of "I Wonder," previously recorded by the Ronettes and the Crystals, retains the crooning backing harmonies, but Spike's vocals have some of the atonal zest of Poly Styrene from X-Ray Spex. The best songs, "Too Fast" and "17-18," have the band's old verve, teetering on the edge of disaster and offering listeners a rush of adrenaline when the band screeches to a halt at the end. These moments make Diode City a fun album, but Superstupid! has not been shaken from its classic status. ~ Sarah Tomlinson, Rovi Performers: Tsutomu Oikawa - Recorder; Kanako - Guitar, Vocals; Marky "Miyagi" Magmatone - Guitar; Nishi - Piano; Rockin' Enocky Thunderbolt - Guitar; Rockin' Thunderbolt Enocky - Guitar; Shoe - Drums; Shoe. - Drums; Spike - Vocals; Tomoko - Voc

Morovision MVB33024LED OV2 Tactical Flash Light High Intensity Led $446.47 The OPERATIVE OV2 tactical lights are compact and lightweight yet powerful and precise with the versatility you need to face any situation. These pocketsized flashlights pack the power of larger fullsize flashlights at a fraction of their size and weight. The OV2 tactical light system has a modular design to meet the wide variety of today s battlefield needs. Interchangeable On/Off/Momentary push button or remote cable pressure pad switching options and the low profile MILSPEC1913 offset mount provide flexibility in mounting and activation options. The OV2 is available with either an incandescent lamp or a high intensity LED in black foliage green and desert sand. The OV2 also integrates seamlessly with the DBALA3 or the ITALA OTALA visible laser models using the optional dual remote cable switch. Rugged aerospace aluminum MILSPEC Type III hardcoat anodized. Shock absorbing incandescent lamp generates 95 lumens of bright white light. Recoilresistant LEDs produce 150 lumens of intense white light. Deeply knurled nonslip grip. Meets MILSTD810G for adverse environmental conditions. Optional tipoff filters available in blue red and green. Infrared filters available for incandescent lights only. Manufactured in the USA. Waterproof to 20 meters. Two 3volt lithium 123A batteries included in each package. Sold Separately: Low Profile MILSPEC 1913 offset mount. Diameter of Head: 1.0 in./2.5 cm. Environment: Waterproof to 20 meters. Length: with Push Button Tail Cap: 5.25 in./13.3 cm with Remote Cable Tail Cap: 5.5 in./14 cm. LED illuminator: 3 years. Incandescent light: 1 year. Material: Aircraft 6061T6 aluminum housing. Incandescent: 1 hour. LED: 1.5 hours. Battery Type: Two 3volt 123A lithium. Incandescent: High pressure Xenon. LED: High intensity light emitting diode. Incandescent: 95 lumens. LED: 150 lumens.

Morovision MVB33028LED OV2 Tactical Flash Light High Intensity Led $444.37 The OPERATIVE OV2 tactical lights are compact and lightweight yet powerful and precise with the versatility you need to face any situation. These pocketsized flashlights pack the power of larger fullsize flashlights at a fraction of their size and weight. The OV2 tactical light system has a modular design to meet the wide variety of today s battlefield needs. Interchangeable On/Off/Momentary push button or remote cable pressure pad switching options and the low profile MILSPEC1913 offset mount provide flexibility in mounting and activation options. The OV2 is available with either an incandescent lamp or a high intensity LED in black foliage green and desert sand. The OV2 also integrates seamlessly with the DBALA3 or the ITALA OTALA visible laser models using the optional dual remote cable switch. Rugged aerospace aluminum MILSPEC Type III hardcoat anodized. shock absorbing incandescent lamp generates 95 lumens of bright white light. recoilresistant LEDs produce 150 lumens of intense white light. Deeply knurled nonslip grip. Meets MILSTD810G for adverse environmental conditions. Optional tipoff filters available in blue red and green. Infrared filters available for incandescent lights only. Manufactured in the USA. Waterproof to 20 meters. Two 3volt lithium 123A batteries included in each package. Sold Separately:. Low Profile MILSPEC 1913 offset mount. Mechanical:. Diameter of Head: 1.0 in./2.5 cm. Environment: Waterproof to 20 meters. Length: with Push Button Tail Cap: 5.25 in./13.3 cm with Remote Cable Tail Cap: 5.5 in./14 cm. Limited Warranty:. LED illuminator: 3 years. Incandescent light: 1 year. Material: Aircraft 6061T6 aluminum housing. Weight: with Push Button Tailcap: 3.5 oz/99.2 grams with Remote Cable Tailcap Mount: 4.9 oz/138.9 grams. Incandescent: 1 hour. LED: 1.5 hours. Battery Type:Two 3volt 123A lithium. Incandescent: High pressure Xenon. LED: High intensity light emitting diode. Incandescent: 95 lumens. LED: 150 lumens.

Kuryakyn Diode Kit $7.99 "This kit is required when installing LED. lights as turn signals on a motorcycle with a single turn signal indicator light If this diode kit is not installed, power will back feed across the indicator light and all turn signals will f"

Diode Melody $10.38 Description not provided.

HIGH INTENSITY LED FLASHLITE $14.99 HIGH INTENSITY LED FLASHLITE

Samsung Intensity Ii Holster $4.99 SAMSUNG INTENSITY II HOLSTER

Blue Ox 6-Amp Diode BX8864 $12.6 Blue Ox Electrical & Wiring in stock now! Read Blue Ox 6-Amp Diode BX8864 customer reviews. AutoAccessoriesGarage.com has the best selection of Blue Ox Towing & Hitches at the lowest prices around. Blue Ox 6-Amp Diode BX8864 are chosen by auto enthusiasts everywhere to personalize their vehicles. Blue Ox Tail Light Wiring Kit available now at AutoAccessoriesGarage.

Blue Ox 6-Amp Diode BX88159 $72 Blue Ox Electrical & Wiring in stock now! Read Blue Ox 6-Amp Diode BX88159 customer reviews. AutoAccessoriesGarage.com has the best selection of Blue Ox Towing & Hitches at the lowest prices around. Blue Ox 6-Amp Diode BX88159 are chosen by auto enthusiasts everywhere to personalize their vehicles. Blue Ox Tail Light Wiring Kit available now at AutoAccessoriesGarage.

Morovision MVB33000LED OV2 Tactical Flash Light High Intensity LedGlass Lens Remote Cable Tailcap and Pressure Pad Switch $275.89 The OPERATIVE OV2 tactical lights are compact and lightweight yet powerful and precise with the versatility you need to face any situation. These pocketsized flashlights pack the power of larger fullsize flashlights at a fraction of their size and weight. The OV2 tactical light system has a modular design to meet the wide variety of today s battlefield needs. Interchangeable On/Off/Momentary push button or remote cable pressure pad switching options and the low profile MILSPEC1913 offset mount provide flexibility in mounting and activation options. The OV2 is available with either an incandescent lamp or a high intensity LED in black foliage green and desert sand. The OV2 also integrates seamlessly with the DBALA3 or the ITALA OTALA visible laser models using the optional dual remote cable switch. Rugged aerospace aluminum MILSPEC Type III hardcoat anodized. Shock absorbing incandescent lamp generates 95 lumens of bright white light. Recoilresistant LEDs produce 150 lumens of intense white light. Deeply knurled nonslip grip. Meets MILSTD810G for adverse environmental conditions. Optional tipoff filters available in blue red and green. Infrared filters available for incandescent lights only. Manufactured in the USA. Waterproof to 20 meters. Two 3volt lithium 123A batteries included in each package. Sold Separately: Low Profile MILSPEC 1913 offset mount. Diameter of Head: 1.0 in./2.5 cm. Environment: Waterproof to 20 meters. Length: with Push Button Tail Cap: 5.25 in./13.3 cm with Remote Cable Tail Cap: 5.5 in./14 cm. 1 year on tactical light. 3 years on LED illuminator. Material: Aircraft 6061T6 aluminum housing. Incandescent: 1 hour. LED: 1.5 hours. Battery Type: Two 3volt 123A lithium. Incandescent: High pressure Xenon. LED: High intensity light emitting diode. Incandescent: 95 lumens. LED: 150 lumens.

RTL Episode 1

UK question - Automatic Number Plate Recognition - Infra Red ?

The web has lots of info on ANPR but nothing really tells me how it works. As it has to work at night does the camera use an infra-red beam to illuminate the plate. Yes/No ? Even in daylight Yes/No ?

If it does would putting lots of high intensity Infra-red light emitting diodes across the plate defeat the camera. What wavelength LED should be used ?

I tried asking my local police, needless to say they were not helpful.

Ian M

Yes, it uses infrared at night. No, in daylight the sun provides plenty of that for free.

Although "defeating a camera" would be a technically illegal pastime, you would only be able to perform this illegal activity by night. The wavelength is a non-sequitur for various reasons, which will become apparent as you google it.