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CBSE Class 10 · Science

The Human Eye and the Colourful World

Official NCERT chapter from Science (book code jesc1). ExamMaster notes are original teaching at CBSE Class 10 depth.

This lesson follows the official chapter “The Human Eye and the Colourful World” in Science. The words below are ExamMaster’s teaching, not a paste from the book. Use the NCERT chapter for the classroom sequence; use these notes to hold the idea without copying exercises or figures.

  • CBSE Class 10
  • Medium level
  • 8 concepts

1THE HUMAN EYE

The human eye is a camera-story at school size: a window, a coloured ring, a hole, a lens, a screen at the back — as the lesson named the parts and jobs. The image on the back-screen is the look; the brain-story if named stays one sentence. Eye is a parts-plus-jobs list, not a medical lecture.

A selfie-eye is not the parts-list.

Figure. The eye is a path: cornea, a thin lens cut, then a retina screen. Rays that pass the lens meet on the screen. No circular globe is drawn.

How it works

  1. Name two parts and their jobsWindow, lens, screen — as taught.
  2. Say the back-screen holds the imageThe look.
  3. Keep the list school-sizeNo extra surgery how-to.

2DEFECTS OF VISION AND THEIR CORRECTION

Defects of vision: a near-job fail (distant blur) or a far-job fail (near blur), as taught, each with a lens-type that corrects (diverging or converging as the lesson paired them). Defect is a named fail plus a named corrector, not a classmate stamp.

Diagnosing a friend from one squint is not a classroom measurement.

Figure. Myopia: the eye's own lens meets the bundle in front of the retina. A diverging strip in front spreads the bundle so the same eye meets it on the screen.

How it works

  1. Name the fail (distant or near)The defect.
  2. Name the correcting lens-type as taughtThe pair.
  3. Stop — no extra clinic how-toSchool size.

3REFRACTION OF LIGHT THROUGH A PRISM

A prism bends light toward the base (as taught) — two refractions, one at each face. The ray sketch is the method. Prism is a triangle-glass job, not a rainbow poster yet (that is the next heading).

A chandelier photo is a setting.

Figure. A prism is three edges, not a rounded block. Air into glass bends toward the normal; glass into air bends away. The two bends add, so the ray leaves toward the base.

How it works

  1. Draw the two faces and the two bendsThe prism.
  2. Mark toward the base as taughtThe rule.
  3. Keep colour-split for the dispersion heading if that is separateThis is the bend.

4DISPERSION OF WHITE LIGHT BY A GLASS PRISM

Dispersion: white light splits into a taught colour-band through a prism because each colour bends a little differently, as the lesson said. Dispersion is the split, not “any pretty colour”. A single-colour beam that does not split is the contrast.

A painted rainbow is not this split.

Figure. One white bundle enters. Glass slows violet more than red, so the violet edge bends farther toward the base. Two exit rays are the spectrum, not a painted rainbow.

How it works

  1. Send white light into the prism as taughtThe given.
  2. Name the band as the lesson ordered itThe split.
  3. Call that dispersionDifferent bends.

5ATMOSPHERIC REFRACTION

Atmospheric refraction is a bend in air that is not uniform — a twinkle-story or an apparent-shift of the Sun, as taught. Atmosphere is the changing medium. A space-photo with no air is not this heading.

A city-twinkle from heat-haze may be the school story if the lesson used it — still a bend, not a new star.

Figure. Sunset light crosses stacked air layers. Each denser slab bends the ray toward the normal, so the sun is still seen after it has gone geometrically below the ground line.

How it works

  1. Name air as a changing mediumThe atmosphere.
  2. Name the look (twinkle, a shift) as taughtThe refraction.
  3. Keep it a bend-storyNot a new object.

6SCATTERING OF LIGHT

Scattering: bits in the air send colours sideways differently — blue-sky and reddened-Sun stories as taught. Scatter is that send-sideways, not a paint. A clean-vacuum thought has no scatter.

A blue poster is not the sky-test.

Figure. White sunlight hits air. Blue is sent sideways and becomes the sky. The leftover beam is redder and is what a long path at the horizon still carries.

How it works

  1. Name the bits and the send-sidewaysScatter.
  2. Tie blue-sky or red-Sun only as the lesson didThe look.
  3. Refuse a paint-explanationPhysics-job, not pigment.

7A definition is a test you can run

Eye / prism / scatter is a test: a parts-list, a defect-plus-lens, a split, or a send-sideways. If you only say “see”, you have a heading.

A sunglasses advert is not the test.

Figure. A school definition is a test you can run on a case. If the case passes, you may use the name. If it fails, stop — do not stretch the word.

How it works

  1. Name part, defect-pair, split, or scatter-lookThe object.
  2. Give the school sentenceThe test.
  3. Then the word has contentThe definition ran.

8Name the given before the unknown

The given is the fail or the look (twinkle, blue sky). The unknown is the corrector or the heading. Copy “distant blur” before you pick a lens.

A fashion-ad “blue light” is not the given scatter.

Figure. Write the given with units first. Only then apply the one relation this heading owns. Hunting the unknown first is how a sign or a unit slips.

How it works

  1. Copy the fail or the lookThe given.
  2. Name lens-type or the headingThe unknown.
  3. Stay with the lesson’s pairsGiven first.
A distant-blur defect (as taught) is corrected by
  1. The lens-type the lesson paired with that fail
  2. Any sunglasses
  3. A prism only

Named fail, named corrector.

Notes

  • Mapped to the official NCERT chapter “The Human Eye and the Colourful World”. Original teaching only — no textbook sentences.
  • Science here is Physics, Chemistry and Biology ideas at this class, never a language or social-science chapter.

Recap

Hold these pegs from the official chapter “The Human Eye and the Colourful World”. The wording is ExamMaster’s teaching, not a textbook recap.

THE HUMAN EYE
The human eye is a camera-story at school size: a window, a coloured ring, a hole, a lens, a screen at the back — as the lesson named the parts and jobs.
DEFECTS OF VISION AND THEIR CORRECTION
Defects of vision: a near-job fail (distant blur) or a far-job fail (near blur), as taught, each with a lens-type that corrects (diverging or converging as the lesson paired them).
REFRACTION OF LIGHT THROUGH A PRISM
A prism bends light toward the base (as taught) — two refractions, one at each face.
DISPERSION OF WHITE LIGHT BY A GLASS PRISM
Dispersion: white light splits into a taught colour-band through a prism because each colour bends a little differently, as the lesson said.
ATMOSPHERIC REFRACTION
Atmospheric refraction is a bend in air that is not uniform — a twinkle-story or an apparent-shift of the Sun, as taught.
SCATTERING OF LIGHT
Scattering: bits in the air send colours sideways differently — blue-sky and reddened-Sun stories as taught.

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