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 Form 4 Physics online lessons on thin lenses

Lesson on the Human eye

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Answer Text:
Human eye:
– It consists of a transparent cornea, aqueous humour and a crystal-like lens which forma converging lens system. The ciliary muscles contract or
relax to change the curvature of the lens. Though the image formed at the retina is inverted the brain ‘sees’ the image as upright. For distant
objects ciliary muscles relax while near objects it contracts to control the focal length and this is known as accommodation. When at 25cm away an object appears clearest and this is known as least distance of vision or near point.