Mirrors and Lenses

Question 1

What is the function of the iris?

Answer 1

It controls the amount of light entering the eye and relaxes in bright light

Question 2

What is pupil?

Answer 2

The hole in the centre of iris

Question 3

What is the retina?

Answer 3

The screen at the back of the eye

Question 4

What are the rods?

Answer 4

The cells that behave as brightness indicators

Question 5

What are the cones?

Answer 5

The cells that sense red, green and blue light

Question 6

What are the photoreceptors?

Answer 6

The cells that convert light energy into electrical signals

Question 7

What is the cornea?

Answer 7

The tough, transparent outer surface of the eye that is responsible for the majority of refraction

Question 8

What is the lens?

Answer 8

Convex in nature and enables fine tuning of focus?

Question 9

What happens when you have cataracts?

Answer 9

Cloudy spots appear in the lens, generally due to old age

Question 10

What happens when you have presbyopia?

Answer 10

A general deterioration in long and short distance focus

Question 11

What happens when you have astigmatism?

Answer 11

Difficulty in horizontal and vertical focus

Question 12

What happens when you have myopia (short-sightedness)?

Answer 12

Focusing power is too strong, lens is thicker than normal and distant objects are blurry

Question 13

What happens when you have hyperopia (long-sightedness)?

Answer 13

Lens system is too weak and near objects are hard to focus on

Question 14

What is the corrective measure for myopia?

Answer 14

Concave lenses are required to diverge light rays and allow stronger lens to refocus the image

Question 15

What is the corrective measure for hyperopia?

Answer 15

Convex lenses are required to enable greater refraction to compensate for weaker lens

Question 16

What do all plane mirrors show?

Answer 16

A virtual image of the same size

Question 17

If you are standing six metres away from a plane mirror, how far away is the image from you?

Answer 17

Twelve metres away

Question 18

What do concave lenses do?

Answer 18

Bulge inwards away from the incident ray

Question 19

What do convex lenses do?

Answer 19

Bulge outwards towards the incident ray

Question 20

What are convex and concave lenses also known as?

Answer 20

Convex lens are known as converging lens, concave lens are known as diverging lens

Question 21

What do convex mirrors do?

Answer 21

Make light rays diverge and have a virtual focus behind the mirror

Question 22

What do flat mirrors show?

Answer 22

A virtual, laterally inverted image which is the same distance behind the mirror as the object is in front

Question 23

What is the relationship between the curvature and focal length of a concave mirror?

Answer 23

The greater the curvature, the shorter the focal length

Question 24

When does specular reflection occur?

Answer 24

With a glass mirror

Question 25

When does transparent transmission reflection occur?

Answer 25

With plastic wrap

Question 26

When does translucent transmission reflection occur?

Answer 26

With baking paper

Question 27

When does opaque absorption reflection occur?

Answer 27

With a black jumper

Question 28

When does diffuse reflection occur?

Answer 28

With aluminium foil