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Grade 8 · Science · Unit 14 of 22

Lenses, Eyes & Optical Devices

Microscopes, telescopes, cameras and the eye

What your child practises

How lenses form images, how the eye and a camera are alike, how microscopes and telescopes extended what scientists could see, and how technology helps vision and stores images.

Alberta Curriculum learning outcome: Unit C: Light and Optical Systems · convex and concave lenses, image formation, vision and the eye, microscopes, telescopes, cameras and digital imaging

Sample questions

A taste of this unit. In the app, questions change every time and get easier or harder to match your child.

  1. Question 1

    A magnifying glass held close to a page makes the print look larger. Which kind of lens is it?

    • opaque
    • convex
    • plane
    • concave
    Show answer

    convex

    Hint: A convex lens can spread an image to look larger when you are close.

  2. Question 2

    A lens that is thicker in the middle is called…

    • opaque
    • concave
    • convex
    • flat
    Show answer

    convex

    Hint: Convex lenses bulge outward.

  3. Question 3

    Farsighted people see far things clearly but have trouble with near things. What kind of lens helps?

    • a prism
    • a convex lens
    • a mirror
    • a concave lens
    Show answer

    a convex lens

    Hint: A convex lens bends light inward a little before it enters the eye.

  4. Question 4

    What does a convex lens do to parallel rays of light?

    • It stops them.
    • It spreads them apart.
    • It brings them together at a point.
    • It turns them into sound.
    Show answer

    It brings them together at a point.

    Hint: A convex lens is a converging lens.

  5. Question 5

    Eyeglasses with concave lenses help someone who is nearsighted. What do they do?

    • Block most of the light.
    • Replace the retina.
    • Spread the light slightly before it enters the eye so it focuses on the retina.
    • Make the image smaller and blurry.
    Show answer

    Spread the light slightly before it enters the eye so it focuses on the retina.

    Hint: Nearsighted eyes focus light in front of the retina. A concave lens fixes this.

  6. Question 6

    The image formed on the retina is…

    • not made by the eye
    • right side up and bigger
    • upside down, and the brain turns it the right way up
    • a sound
    Show answer

    upside down, and the brain turns it the right way up

    Hint: The lens makes an inverted image, and the brain interprets it.

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