Curved Mirrors, the Mirror Equation and Real Images · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Where curved mirrors put images

Science · Waves, Light & Sound · ages 19-20
Name ______________________   Date ____________

  1. Which three principal rays locate an image in a spherical mirror?

    • Parallel then through focus, through focus then parallel, and straight at the centre
    • Any three rays drawn at random angles
    • Three rays all parallel to the axis

  2. A concave mirror has radius of curvature 20 cm. What is its focal length?

    • Equal to the radius
    • Twice the radius
    • Half the radius

  3. A shaving mirror with your face inside its focal length gives a virtual upright image behind the glass. True or false?

    Circle one:   True   False

  4. Why do car wing mirrors use convex glass?

    • They magnify and narrow the field
    • They give real images on a screen
    • They shrink the view and widen the field

  5. An object sits beyond the focus of a concave mirror. What kind of image forms?

    • Real and inverted, projectable on a screen
    • Virtual and upright behind the mirror
    • Real and upright in front of the mirror

  6. How do you catch a sign mistake after a ray construction?

    • Check the ray construction against the mirror equation
    • Ignore the construction and trust the first ray alone
    • Redraw with random rays instead

  7. Telescope makers want sharp images from wide mirrors. What fixes the off axis blur?

    • A paraboloid primary, which brings parallel rays to a single point
    • A wider spherical mirror used far off axis
    • A convex mirror placed behind the eyepiece

  8. What is spherical aberration, and when does it bite?

    • The mirror equation stops working near the axis
    • Off axis rays miss the shared focus and blur the image
    • The focal length becomes twice the radius
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Where curved mirrors put images W1-mt_7XqB2umthJ-s1

  1. Parallel then through focus, through focus then parallel, and straight at the centre · Where those three rays cross, or appear to cross, is the image.
  2. Half the radius · Parallel rays meet nearly at the focus halfway between mirror and centre of curvature.
  3. True · The object inside focus gives reflected rays that only appear to meet behind the mirror.
  4. They shrink the view and widen the field · Convex mirrors minify and widen the field at the cost of smaller images.
  5. Real and inverted, projectable on a screen · Beyond focus the image flips to real and inverted, projectable onto a screen.
  6. Check the ray construction against the mirror equation · The equation links object distance, image distance, and focal length, catching sign mistakes.
  7. A paraboloid primary, which brings parallel rays to a single point · Parabolic figures fix spherical blur by design, which is why telescope primaries use them.
  8. Off axis rays miss the shared focus and blur the image · Spherical aberration grows with aperture, so wide fast mirrors need correction.
Worksheet · LightMySky