AQA GCSE Biology · 8461
Specification 4.5.2.3 · Paper 2
- Revise: Vision Defects and Corrections
A lens that is thinner in the middle than at the edges and spreads out, or diverges, light rays.
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GCSE Biology · key term
A lens that is thinner in the middle than at the edges and spreads light rays apart.
Used by AQA, Edexcel and OCR
Specification 4.5.2.3 · Paper 2
A lens that is thinner in the middle than at the edges and spreads out, or diverges, light rays.
Specification 2.17B · Paper 1
A lens that is thinner in the middle than at the edges and spreads light rays out.
Specification B3.1e · Paper 1 (Foundation), Paper 3 (Higher)
A lens that is thinner in the middle and spreads light rays apart.
Revise: Eye defectsA concave lens, which is thinner in the middle, corrects short-sightedness. It diverges the incoming rays slightly before they enter the eye. The eye then brings these rays to a focus farther back, exactly on the retina.
Paper 1 (Foundation), Paper 2 (Foundation), Paper 3 (Higher), Paper 4 (Higher)
Revise: Eye DefectsA concave lens, which is thinner in the middle, spreads the rays apart slightly before they enter the eye. The eye then brings them together farther back, on the retina. In a ray diagram, compare the point where the uncorrected rays meet with their meeting point after passing through the concave lens.
Check the lens shape as well as its name: a concave lens is thinner in the middle and corrects myopia; a convex lens is thicker in the middle and corrects hyperopia.
Check the pairing: short-sightedness needs a concave lens; long-sightedness needs a convex lens.
Do not reverse the corrective lenses: short-sightedness is corrected by a concave lens; long-sightedness is corrected by a convex lens.
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