telescopes, microscopes, eyes, night-vision devices Flashcards
Who made telescopes?
Newton, Galileo, Kepler
What are the main parts of the telescope?
Eyepiece, objective
What are binoculars like?
2 refracting telescopes with 2 prisms that act as mirrors
What are microscopes like?
Similar to Kepler’s telescopes
What do the eyes do?
Focuses on objects at different distances, record images, detect subtle changes in colour and brightness.
How do eyes focus?
Front of the eye. Everything else is behind.
What are the cones and rods for?
Light, Colour
What does the cornea do?
Refracts light before it enters the eye
What does the retina do?
Layers of cones + rods behind the eye that respond to light and initiate nerve impulses.
What do the ciliary muscles do?
Change the shape of the lens by shortening/thickening.
How does the lens change to look at closer objects?
Lens must be thicker (rounder).
What are the lens, retina, and pupil of cameras?
Camera lens (in and out), film or CCDs, apertures.
What is myopia?
Near-sightedness, image forms in front of the retina, diverging lens.
What is hyperopia?
Far-sightedness, rays don’t meet before the retina, converging lens.
What is presbyopia?
Lenses are stiff, can’t focus on nearby objects, bifocals.
What is astigmatism?
Incorrectly-shaped cornea, blurred/distorted vision.
What does laser eye surgery do?
Removes (vapourizes) parts of the cornea to change the shape and how it refracts light.
How does laser eye surgery work?
Flap is cut in cornea + pulled back, surface shaped by laser, flap is replaced
What are night-vision devices?
Allows people to see when there is little light.
How do night vision devices work?
Image-intensifier tube uses a high-voltage power supply to increase the amount of light reaching the eyes.
