Optics and Lenses Quiz

Magnifying Glass

• Produces a magnified (larger) image of an object
• Produces an upright, magnified virtual image

Lenses and Images

• An image forms where light rays converge
• Double (bi) Convex lenses:
  • Mirror and invert images when far away from the lens
  • Used in film and overhead projectors

Eyes

• Lens (eye): a convex lens that focuses light allowing us to see objects
• Retina: cells inside the eye that absorb light and send a signal to the brain
• A. Far-Sighted:
  • Image falls behind the retina
  • Trouble seeing objects close to them
  • Corrected with a convex lens
• B. Near-Sighted (short-sighted):
  • Image forms in front of the retina
  • Trouble seeing objects further away
  • Corrected with a concave lens

Eye vs Camera

• Similarities:
  • Both have lenses that bend and transmit light
  • Both have an aperture that controls the amount of light
• Differences:
  • Eye: retina, iris, and pupil
  • Camera: film, diaphragm, and aperture

Focus

• Accommodation: the process of changing the shape of the lens to adjust for object distances
• Near Point: the shortest distance at which an object is in focus
• Far Point: the longest distance at which an object is in focus

Blind Spot

• Optic Nerve: absorbs signals from the retina and transports them to the brain
• The point where the optic nerve is does not have retina cells, creating a blind spot

Structure and Function of the Eye

• Pupil: space where light passes through
• Cornea: exterior of the eye covering the lens
• Lens: transparent convex lens that focuses light
• Iris: muscle that controls the amount of light entering
• Ciliary muscle: changes the shape of the lens to help focus/adjust
• Aqueous humour: liquid between the lens and cornea
• Vitreous humour: transparent jelly that fills the interior of the eyeball
• Retina: membrane that absorbs light
• Optic nerve: transports signals from retina to the brain

Telescopes

• Refracting Telescopes:
  • Use convex objective lens and convex ocular lens (eyepiece)
• Reflecting Telescopes:
  • Use concave mirror (primary or objective mirror) and plane mirror
  • Convex ocular lens (eyepiece)
• Characteristics:
  • Lenses and mirrors collect light and must be large to collect as much as possible from distant objects
  • The farther the image from the lens/mirror, the greater the magnification

Hubble Space Telescope

• A powerful orbiting telescope that provides sharper images of heavenly bodies
• Features a light-gathering mirror 94 inches (240 centimeters) in diameter
• Named after American astronomer Edwin P. Hubble

James Webb Space Telescope

• A joint NASA-ESA-CSA space telescope that will succeed the Hubble Space Telescope
• Launch date: October 31, 2021

Binoculars

• Like 2 telescopes
• Use prisms to bend light
• Use convex lenses (ocular and objective)

Microscopes

• Use convex lenses (ocular and objective)
• Use for magnifying small objects