Essay on Light and Light Sensors

Submitted By 4twirjkl
Words: 539
Pages: 3
Open Document
PHOTORESISTORS

A few examples of devices that need light sensors to function properly:

Car headlights that automatically turn on when it’s dark
Streetlights that automatically turn on when it gets dark
Outdoor security lights that turn on when someone walks by (but only at night)
Laptop displays that get brighter in well lit areas and dimmer in poorly lit areas
Cameras with automatic exposure settings

The first three examples in the list are automatic lighting, and they depend on ambient light sensors to distinguish day from night. The electronics inside those devices only needs to know whether it’s light or dark, so they can treat their light sensors as binary outputs like pushbuttons. Laptop displays and camera auto exposures adjust to area lighting conditions by getting information from their light sensors about how bright or dark it is. They have to treat their light sensors as analog outputs that supply a number that indicates how bright or dark it is, much like previous potentiometer examples where numbers indicated the knob’s position.

INTRODUCING THE PHOTORESISTOR

Light sensors have many different functions, and they come in different shapes, sizes, and with different price tags. Some sensors are designed to sense a particular color of light, such as blue, green, red, or infrared. Some sensors don’t care what color the light is because they react to how bright the light is. Other sensors look for only special kinds of light given off by certain chemical reactions. Light sensors also have a variety of ways to tell a microcontroller what they see. Some sensors send a voltage, some send a sequence of binary values, and others react to different kinds of light or light levels by changing resistance.

Of the light sensors that react to light by changing their resistance, the photoresistor is probably the most common, least expensive and easiest to use. Its active ingredient is a chemical compound called cadmium sulfide (CdS). This compound changes resistance depending on how bright the light is that shines on its collecting surface. Bright light causes low resistance values between the
Show More

Related Documents: Essay on Light and Light Sensors

Assignment: Iphone and Ambient Light Sensor Essay

* Processors * Touch displays * Software These core products can be further broken down to show the corresponding core technology: * Multi touch technologies * Automatic rotation (gyro) * Virtual keyboard * Ambient light sensor * Software * Production technology * Design * Customized Processor’s Resourses: * http://winsupersite.com/product-review/apple-iphone-review-part-2-core-technologies * https://developer.apple.com/technologies/mac/core…

Words 890 - Pages 4

Assignment 2 Design Operation Essay

terms motors are the actuators that drive the joints. You could say that the motors are the muscles that manipulate the joints. The motors must be powerful enough to drive the load through acceleration and deceleration but must also be responsive, light, accurate and reliable. Electric motors are the most common type with servo, stepper and direct drive motors being found. With all electric motor the torque (power output) is a direct function of the magnetic fields and the current in the windings…

Words 3433 - Pages 14

absorption spectroscopy Essay

“diffraction grating” in the index. 2. Serway, Moses, and Moyer, Modern Physics, Third Edition, Sections 4.3 and 9.3. Diffraction Grating Spectroscopy We will use a transmission diffraction grating to view the visible emission lines from hydrogen and sodium light sources. A diffraction grating is a device with a very large number of closely spaced slits. The advantage of a grating over a simple double slit is that the lines can be made very close to each other. As you may recall from introductory physics, this…

Words 5518 - Pages 23

Essay on Digital Photography

considered the first digital image. In 2003, Life magazine selected this picture as one of the “100 photos that changed the world”. The 1960’s marked significant developments to digital photography. In 1961, Eugene Lally tried to use a mosaic photo sensor to create digital photos or images. Nothing came of this idea until twenty years later when Sony produced a camera based on his idea. The next advancement was 1966 when NASA began to gather data on the moon by mapping its surface. The analog signals…

Words 3049 - Pages 13

Camera: Photography and Lens Essay

Camera: Lens The lens is one of the most vital parts of a camera. The light enters through the lens, and this is where the photo process begins. Lenses can be either fixed permanently to the body or interchangeable. They can also vary in focal length, aperture, and other details. Viewfinder The viewfinder can be found on all DSLRs and some models of digital compacts. On DSLRs, it will be the main visual source for image-taking, but many of today’s digital compacts have replaced the typical…

Words 1008 - Pages 5

Informative Speech On Vertical Farming

Mobile tech is playing a big role in monitoring and controlling crop irrigation systems. With the right equipment a farmer can control his irrigation systems from a phone or computer instead of driving to each field, moisture sensors in the ground are able to communicate information about the level of moisture present at certain depths in the soil. This increased more control of water and other inputs like fertilizer that are applied by irrigation pivots. Farmers can also combine…

Words 994 - Pages 4

Spinach Photosynthesis Lab

the light was to the spinach leaf the more O2 that was created which increased the rate of photosynthesis in the spinach leaf. We addressed this problem by using the same light intensity but at different distances from the plant seeing which distance had the most O2 intake for the plant. Our key observation was light intensity that was being put on the spinach leaf. After going through our trials we have concluded that out of our results they support our hypothesis and with the focused light source…

Words 805 - Pages 4

The Importance Of Blind Spots

is the sharpest. The actual blind spot in the eyes of humans is created because the back of the eye, the retina, is full of sensor cells, also known as rods and cones. These sensor cells send out a signal through the axon, and the location of where these entire axons meet to form the optic nerve, doesn’t have any sensor cells. This creates a blind spot because the sensors can’t overlay the nerve bundle at that point on the retina. We also learned in our psychology class that octopi do not have…

Words 317 - Pages 2

Garage Door Opener Research Paper

proper upkeep and maintenance. In case an issue arises, you are recommended to troubleshoot and fix it yourself before calling a professional to fix it for you. Some of the key problems that are easy to troubleshoot and fix include the following: - Lights that do…

Words 672 - Pages 3

Essay about Sensor Electrical Services

SENSOR ELECTRICAL SERVICES Rob Lewis Tel: 07809 639 424 E-Mail: Rob@sensorelectricalservices.co.uk Web: www: sensorelectricalservices.co.uk Installation, Inspection and Testing Estimate Date – 12/07/2012 Client – Casazza Kitchens For Works relating to – 14 Dell Way, Ealing, W12 8JH. Description Of Works: Work out existing kitchen ring circuit and test for suitability of alteration and extension for new kitchen layout. Points to be incorporated include: Supply isolator for integrated fridge…

Words 359 - Pages 2