Single-Slit Diffraction and the Limit of Resolution · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

One slit spreads, wide eyes resolve

Science · Waves, Light & Sound · ages 17-18
Name ______________________   Date ____________

  1. Red and violet light share one slit. Which pattern is broader?

    • Violet, shorter waves spread more
    • Red, longer waves spread more
    • Both match exactly

  2. The slit is made narrower. What happens to the central maximum?

    • It grows wider
    • It grows narrower
    • It stays exactly level

  3. A single narrow slit makes a sharp thin stripe of light.

    Circle one:   True   False

  4. Why do astronomers build huge mirrors?

    • To collect less light
    • To narrow the blur and split finer detail
    • To widen the central maximum

  5. How do you tell a double slit pattern from a single slit one?

    • A dominant centre means two slits
    • Even regular fringes mean two slits
    • Faint sides mean two slits

  6. Wavelength doubles through the same slit. What happens to the pattern?

    • The pattern stays level
    • The pattern shrinks
    • The pattern spreads wider

  7. Two close stars blur into one blob in a small telescope. What would separate them?

    • A wider aperture
    • A narrower slit
    • Dimmer eyepiece light

  8. Nadia claims narrowing the slit narrows the pattern. What is her error?

    • She used the wrong colour
    • She mixed up the direction, narrower spreads wider
    • She measured the wrong fringe
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Answer key

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

One slit spreads, wide eyes resolve W1-mt_qiG0fGadBU-s1

  1. Red, longer waves spread more · Longer wavelengths spread more, so red paints the broader pattern.
  2. It grows wider · Narrower gaps spread light more, so the central band widens.
  3. False · It spreads into a broad centre with weak side fringes instead.
  4. To narrow the blur and split finer detail · Wider apertures narrow each diffraction blur, so close points stay separable.
  5. Even regular fringes mean two slits · Two sources interfere into a comb of even fringes, while one slit gives a dominant centre.
  6. The pattern spreads wider · Spreading grows with wavelength, so doubling it widens the pattern.
  7. A wider aperture · A wider aperture narrows each star blur until the two centres split apart.
  8. She mixed up the direction, narrower spreads wider · The slit rule runs backwards: tighter gaps spread light wider, not narrower.
Worksheet · LightMySky