Light sensors may be used in burglar alarms or inside garage door openers. Light shines between sensors, and if the something interrupts the light, the device knows an object’s there. In addition, they are also used in street lights to determine when it's dark enough for the light to switch on.Know More
In the case of a burglar alarm, the light sensor constantly senses a beam of light from another part of the alarm. If a person or object gets in the way of the beam, the sensor knows senses the change in light and immediately sound the alarm. Garage door devices need a similar set up in order to make sure they don’t close on top of an object. If the light bouncing back from the ground is interrupted, then the garage door doesn't close to prevent damage.
Bar code scanners also use light sensor technology. The light in the scanner reflects on bar code, and then a sophisticated light sensor inside picks up on the patterns of light to translate the code into numbers and other data. Motion-sensing devices often have light sensors in them as well. Human beings give off infrared light, and many businesses use infrared sensors to automatically open their doors when someone approaches. A number of motion-sensing lights also use this approach.Learn more in Optics & Waves
Light energy is a type of kinetic energy with the ability to form types of light people can see as well as invisible waves. Light is a form of electromagnetic radiation, and hot objects, such as light bulbs, the sun and lasers, emit it.Full Answer >
Light manifests properties of both a particle and a wave, depending on the nature of the measuring apparatus used. Albert Einstein's photoelectric effect, explained in 1905, highlights the particle nature of light in terms of frequency and intensity of electron emissions. The wave nature is evident in large-scale applications.Full Answer >
A light ray is a basic element in geometrical optics. It is a hypothetical construct that, from any point in space, indicates the propagation of light. The concept that light travels in straight lines led to the development of the light ray concept.Full Answer >
The human eye sees light with the pupil and the retina. Located inside the retina are two types of special cells called photoreceptor cells. There are two varieties of photoreceptor cells known as cones and rods.Full Answer >