PHYSICS XG: Eyes

7/28/2019 PHYSICS XG: Eyes

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OpticalInstruments

Eyes

CristarikaFredick

Natasia

Riky


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Introduction of Eyes

Eyes are one of the optical instruments It contain convex lens

can distinguish about 10 million colors

consisting of various muscles, tissues, andnerve sensors


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The components of eyes

(that are related to the vision process)

Cornea

Pupil

Iris

Lens

Cilliary muscle

Retina

Optical nerves

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How light enters

Light enters the cornea.

Its intensity is controlled by the iris.

The light passes through the iris opening called the

pupil, and is focused by the retina.

Conducted by the optic nerve and tract to the backpart of the brain.

FLASH

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CORNEA Protective and transparent layer

(covers the iris and pupil) In human the refractive power of thecornea is approximately 43 dioptres

In front of the eye

BACK


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PUPIL

BACK

The circular opening in the center of the pigmented

iris of the eye

Through which light passes to the retina

Dim light = pupil gets bigger

Bright light = pupil gets smaller


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IRIS

Give colors Manage the number of slices of light

Controlling the size of the pupils and amount of light

BACK


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LENS

Held by cilliary muscle Can set the eyes thickness See objects at various distances

BACK


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CILLIARY MUSCLE

Controls accommodation for viewing objects at varyingdistances

Regulates the flow of aqueous humour

It changes the shape of the lens within the eye

BACK


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RETINA

Sensitive to light

Image fall on it with the nature of image that

real and inverted

BACK


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OPTICAL NERVES

Transmits visual information from the retina

to the brain

BACK


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CILLIARY MUSCLE

IRIS

CORNEALENS

7PUPIL

RETINA

OPTICAL NERVES

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The eyes sickness

Normal eyes

Short sighted (myopia)

Far sighted (hypermetropia) Presbyopia

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Normal eyes

Near point = 25cm

Far point = infinity

BACK


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Short-sightedness (Myopia)

Distant objects appear blurred

Far point < infinity

Use concave lens to help

Sample Equation

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Page 148

No.1) A far point for a person with short-

sightedness is 1.2m. Calculate the optical

power of lens!

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Far-sightedness (Hypermetropia)

Cannot see close objects clearly

Near point > 25cm

Use convex lens to helpFLASH

Sample Equation
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Page 149

No.1) A punctum proximum of a person with

hypermetropia is 50 cm. He would like to read atdistance of 20 cm. Calculate the optical power of lens

that is used!

BACK


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BACK


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Accommodation

Accommodation is process of managing the

thickness of lens or changing the optical power.

The purpose of accommodation is to make

objects at various distances can form an image

on the retina.

Back


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The range of optical power of eye


accommodation is the maximum change of

power in accommodation. Or the range between the maximum

accommodation and the minimum

accommodation.

Sample Equation

accommodation


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accommodation equation


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Example

Suppose the distance from the lens of an eye

to the retina is 3 cm. Find the range of optical

power of eye accommodation!


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Thank You

For YourAttention

PHYSICS XG: Eyes

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