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What is a handheld device that can detect the presence of light?
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What are photoelectric sensors used for?
Photoelectric sensors use light to detect the presence, absence, or distance of an object. They often use the infrared spectrum of light, though visible light is also used.
What is a lightpen?
A light pen is: a handheld, penlike photosensitive device held to the display screen of a computer terminal for passing information to the computer. That's a definition I got off the computer
How does refraction allow you to see?
The refraction of light by the cornea and lens of the eye makes it possible for an image to form on the retina. Without the formation of an image, it would be possible for the retina to detect the presence or absence of light, but not shapes or objects.
Why cant humans detect infrared light?
They can. While human eyes can not "see" infrared light, humans can detect this light as "heat" on the surface of the skin.
Why is it necessary to detect radiation from space and not just light?
Light is radiation.
What makes us to see something?
The presence of light and our visual organs that detect that light.
What receptor cells in the eye detect the presence or absence of light?
Rods
What are photoelectric sensors used for?
Photoelectric sensors use light to detect the presence, absence, or distance of an object. They often use the infrared spectrum of light, though visible light is also used.
Can any other device except for eyes detect light?
There are artificial detectors (photo receptors) that can sense light. They're commonly used in security applications.
What is a lightpen?
A light pen is: a handheld, penlike photosensitive device held to the display screen of a computer terminal for passing information to the computer. That's a definition I got off the computer
What detects infrared light?
Light doesn't detect anything, no matter what its wavelength is.If you BUILD a detector that responds to infrared, then your detector will respond to heat.It can be used to reveal the presence of stoves, people, fresh coffee, dogs, etc., even in thedark where your eyes cannot detect them.
What was the first living thing that could see?
The oldest recorded organism that had photosensitive sensory organs with the ability to detect the presence and direction of light within a few degrees of accuracy was a prehistoric sea snail that existed approximately 550 million years ago. Organisms that could detect the presence but not the direction of light probably evolved earlier, but no fossils of these organisms have been found.
How are the wavelength of visible light seen?
In your eyes are two groups of light detecting sensors at the Retina. Cones detect colour and rods detect light. The Cones are further divided into sensors for three different colours, (red, blue, and green) but their colour sensitivities overlap, so we see our full colour spectrum.The Rods are much more sensitive than the cones, but only detect the presence of light. That is why generally you cannot determine colours at night.
How does refraction allow you to see?
The refraction of light by the cornea and lens of the eye makes it possible for an image to form on the retina. Without the formation of an image, it would be possible for the retina to detect the presence or absence of light, but not shapes or objects.
What uses a device that emit and sense light to detect the mouse's movement?
Optical mouse: Most desktop computer users today have some type of optical mouse, which uses devices that emit and sense light to detect the mouse's movement.
The cells in the retina of the eye that detect light are called what?
Rods are sensitive to absence of light cos they are responsible for night vision or black and white vision while cones are sensitive to presence of light cos they are responsible for colour vision
Why cant humans detect infrared light?
They can. While human eyes can not "see" infrared light, humans can detect this light as "heat" on the surface of the skin.
