3.1.4 The eye

Question 1

Name the main parts of the eye.

Answer 1

■ retina
■ lens
■ cornea
■ pupil /iris
■ ciliary muscle
■ suspensory ligaments

Question 2

What is farsightedness?

Answer 2

long sight, caused by the eyeball being too short,

or the eye lens being unable to focus

Question 3

What is nearsighted?

Answer 3

short sight, caused by the eyeball being too long,

or the eye lens being unable to focus.

Question 4

What are the near and far points?

Answer 4

Candidates should know that the near point is

approximately 25 cm and the far point is infinity

Question 5

What is the focal length of the lens determined by?

Answer 5

■ the refractive index of the material from which the
lens is made, and
■ the curvature of the two surfaces of the lens.

Question 6

What does a higher refractive index mean

Answer 6

For a given focal length, the greater the
refractive index, the flatter the lens. This means
that the lens can be manufactured thinner