Physics P3 1.7 The eye.

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How is light focused on to the retina?
By the cornea and the eye lens, which is a variable focus lens.
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What is the range of vision of a normal human eye?
It has a near point of 25 cm and a far point of infinity, so its range of vision is from 25 cm to infinity.
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How does light enter the eye?
Through the cornea.
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How is the amount of light that enters the eye controlled?
The iris adjusts the size of the pupil to control the amount of light entering the eye.
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What controls the fine focusing of the eye?
The ciliary muscles alter the thickness of the lens to control the fine focusing of the eye.
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How are the ciliary muscles attached to the lens?
By the suspensory ligaments.
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What does the eye lens do?
Focuses light onto the retina.
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What is the iris?
The coloured ring of muscle that controls the amount of light entering the eye.
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What is the cornea?
The transparent layer that protects the eye and helps to focus light onto the retina.
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What is the pupil?
The central hole formed by the iris, light enters the eye through the pupil.
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What are the ciliary muscles?
The muscles attached to the lens by suspensory ligaments, the muscles change the thickness of the eye lens.
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What is the retina?
The light-sensitive cells around the inside of the eye.
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What is the blind spot?
The region where the retina is not sensitive to light (no light-sensitive cells present).
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What carries nerve impulses from the retina to the brain?
The optic nerve.
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What is the equation for the power of a lens?
P = 1 over f (look up).
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What is the P in the equation for the power of a lens?
The power of the lens in dioptres (D).
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What is the f in the equation for the power of a lens?
The focal length of the lens in metres (m).
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Which two structures focus the light entering the eye?
Cornea and lens.
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What is the power of a lens of focal length 0.25 m?
4.0 d.
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**WHEN CAL ULATING THE POWER OF A LENS, MAKE SURE THAT THE FOCAL LENGTH IS IN METRES SO THAT THE POWER OF THE LENS IS IN DIOPTRES**
**LOOK UP DIAGRAM OF THE EYE AND LABEL**
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Other cards in this set

Card 2

Front

What is the range of vision of a normal human eye?

Back

It has a near point of 25 cm and a far point of infinity, so its range of vision is from 25 cm to infinity.

Card 3

Front

How does light enter the eye?

Back

Preview of the front of card 3

Card 4

Front

How is the amount of light that enters the eye controlled?

Back

Preview of the front of card 4

Card 5

Front

What controls the fine focusing of the eye?

Back

Preview of the front of card 5
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