Lenses

Question 1

Convex sides:

Answer 1

Makes light rays converge together

Question 2

Concave sides:

Answer 2

Makes light rays diverge apart

Question 3

Converging lens:

Answer 3

Convex sides

Question 4

Diverging lens:

Answer 4

Concave sides

Question 5

What is the cornea:

Answer 5

A clear part of the eye in front of the iris

Question 6

What is the iris:

Answer 6

The coloured part of the eye, and it is made of muscle

Question 7

What is the lens:

Answer 7

A clear, oval shaped part of the eye that is behind the iris

Question 8

What are the suspensory ligaments:

Answer 8

They are attached to the end of the lens and to the ciliary muscles

Question 9

What is the vitreous humour:

Answer 9

The jelly in the back section of the eye

Question 10

What is the retina:

Answer 10

A layer of cells on the back of the eye

Question 11

What are the ciliary muscles:

Answer 11

They are attached to the lens via the suspensory ligaments

Question 12

What is the blind spot:

Answer 12

The place at the back of the eye where the blood vessels and nerves join the eyeball

Question 13

What is the optic nerve:

Answer 13

A nerve at the back of the eye that leads to the brain

Question 14

What is the pupil:

Answer 14

A gap in the iris

Question 15

How does long-sightedness occur:

Answer 15

The lens in your eye doesn’t focus the light until it is past the retina

Question 16

How does short-sightedness occur:

Answer 16

The lens in your eye focuses the light before the retina

Question 17

Define myopia:

Answer 17

Short-sightedness

Question 18

How do glasses work:

Answer 18

They partially focus the light so your lens focuses the altered light onto the retina

Question 19

Which type of incorrect sight has a lens too thick:

Answer 19

Short-sightedness

Question 20

Which type of incorrect sight has a lens too thin:

Answer 20

Long-sightedness

Question 21

Define object:

Answer 21

What you look at through a lens or optical instrument

Question 22

Define image:

Answer 22

What you see through a lens or optical instrument

Question 23

Define upright:

Answer 23

The image is the same way up as the object

Question 24

Define inverted:

Answer 24

The image is upside down to the object

Question 25

Define real:

Answer 25

There is no need to extend the rays to find the image

Question 26

Define virtual:

Answer 26

The rays need to be extended to find the image

Question 27

To draw ray diagrams side 1:

Answer 27

One parallel, one through the centre of the lens, one connected to the parallel on the other side

Question 28

To draw ray diagrams side 2:

Answer 28

One from the centre line (doesn’t refract), one parallel, one connected to the parallel on the other side

Question 29

What is the focal length:

Answer 29

The length between the centre of the lens and the focal point

Question 30

What is the nature of an image:

Answer 30

Magnified/diminished (for virtual images), real/virtual, upright/inverted

Question 31

How can you tell the difference between a real and virtual ray diagram that has no extended rays (yet):

Answer 31

A real diagram has the object equal to or longer than the focal length away from the lens on the other side. A virtual diagram is closer than the length of the focal length

Question 32

How do you find the focal point on a diverging/concave lens:

Answer 32

Extend the rays backwards

Question 33

Concave lenses are used to treat:

Answer 33

Short-sightedness

Question 34

Convex lenses are used to treat:

Answer 34

Long-sightedness

Question 35

Magnification formula:

Answer 35

Image height
Magnification = ―――――――
Object height

Question 36

What is the unit for magnification:

Answer 36

None, but if one is specified use it

Question 37

Images formed by concave lenses are always:

Answer 37

Virtual, upright and diminished