P11: Lenses and The Eye

Question 1

Answer 1

Concave (Diverging) Lens

Question 2

Answer 2

Concave (Converging) Lens

Question 3

Uses of a convex lens

Answer 3

Magnifying Glass, In a camera to create a clear image of a far off object.

Question 4

Uses of a concave lens

Answer 4

To correct short sightedness.

Question 5

Focal Length

Answer 5

The distance from the centre of a lens to where the light rays focus (or, in the case of a concave lens, appear to diverge from.)

Question 6

Answer 6

Real Image, from a convex lens.

Question 7

Answer 7

Virtual Image, from a concabe lens

Question 8

Magnification of an image =

Answer 8

Image height/ Object Height

Question 9

How to construct a real image/converging lens diagram

Answer 9

Question 10

How to construct a virtual/Converging lens diagram

Answer 10

Question 11

How to construct a virtual/Diverging lens diagram

Answer 11

Question 12

How does a camera work?

Answer 12

Question 13

What does ‘real is positive’ mean?

Answer 13

Real images are given positive focal lengths in the formula, virtual negative.

Question 14

1/focal length =

Answer 14

1/distance from object to lens + 1/distance from lens to image

(1/u + 1/v = 1/f)

Question 15

A diverging lens…

Answer 15

… always gives a virtual image.

Question 16

Answer 16

Question 17

Iris

Answer 17

Coloured ring of muscle that controls the amount of light entering the eye.

Question 18

Aqueous Humour

Answer 18

Transparent watery liquid that supports the front part of the eye.

Question 19

Cornea

Answer 19

Transparent layer that protects the eye and helps to focus light onto the retina.

Question 20

Pupil

Answer 20

the central hole formed by the Iris. Light enters the eye through the pupil.

Question 21

Ciliary Muscles

Answer 21

Attached to the lens by Suspensory Ligaments.The muscles change the thickness of the eye lens.

Question 22

Eye Muscles

Answer 22

Move the eye in the socket.

Question 23

Optic Nerve

Answer 23

Carries nerve impulese from the retina to the brain.

Question 24

Blind Spot

Answer 24

Region of the retina that is not sensitive to light (no light sensitive cells present)

Question 25

Retina

Answer 25

The light sensitive cells around the inside of the eye.

Question 26

Vitreous Humour

Answer 26

Transparent jelly-like substance that supports the back of the eye.

Question 27

Eye Lens

Answer 27

Focuses light onto the retina.

Question 28

Type of lens (Eye vs Camera)

Answer 28

Variable focus converging lens

Fixed focus convergin lens

Question 29

Focusing Adjustment (Eye vs Camera)

Answer 29

Ciliary muscles adjust lens position.

Manual adjustment of lens position.

Question 30

Image produced (Eye vs Camera)

Answer 30

Both real, inverted, magnification less than 1.

Question 31

Image detection (Eye vs Camera)

Answer 31

Light sensitive cells on the retina

Photographic Film (or CCD sensors in digital camera)

Question 32

Brightness Control (Eye vs Camera)

Answer 32

Iris controls width of pupil

Adjustment of aperture ‘stop’

Question 33

Short Sight

Answer 33

An eye that can only focus on near objects.

Corrected with a diverging lens.

Question 34

Long Sight

Answer 34

An eye that can only see far away objects.

Corrected with a converging lens.

Question 35

Power of a lens (D (dioptre)) =

Answer 35

1/ focal length (m)

Question 36

The higher the refractive index of a lens material…

Answer 36

… The flatter and thinner the lens can be.