P3a- Lenses

Question 0

What does a converging lens cause parallel rays of light to do?

Answer 0

Converge- move together- at the principle focus

Question 1

When waves speed up they bend…

Answer 1

Away from the normal

Question 2

In a converging lens, an incident ray parallel to the axis refracts through the lens and….

Answer 2

Passes through the principle focus on the other side

Question 3

The angle of refraction of a ray depends on the ………….. ……… of that material

Answer 3

Refractive index

Question 4

Every transparent material has a …… ……

Answer 4

Refractive index

Question 4

A converging lenses’ shape is …..

Answer 4

Convex- (bulges outwards)

Question 5

The principle focus of a converging lens is where the…..

Answer 5

Rays hitting the lens parallel to the axis all meet

Question 6

When waves slow down they bend….

Answer 6

Towards the normal

Question 7

What is the refractive index?

Answer 7

The ratio of speed of light in a vacuum to speed of light in that medium

Question 8

To make a more powerful lens, you ….

Answer 8

Give it a more strongly curved surface

Question 10

What are the three rules for refraction in a diverging lens?

Answer 10

An incident ray parallel to the axis refracts through the lens and travels in line with the principle focus (so it appears to have come from the principle focus)
An incident ray passing through the lens towards the principle focus refracts through the lens and travels parallel to the axis
An incident ray passing through the centre of the lens carries on in the same direction

Question 11

What are the three rules for refraction in a converging lens?

Answer 11

An incident day parallel to the axis refracts through the lens at passes through the principle focus on the other side

An incident ray passing through the principle focus refracts through the lens and travels parallel to the axis

An incident ray passing through the centre of the lens carries on in the same direction

Question 12

The principle focus of a diverging lens is the point where the rays hitting the lens parallel to the axis….

Answer 12

Appear to all come from- you can trace them back until they appear to meet up at a point behind the lens.

Question 13

There is a principle focus on each side of the lens. The distance from the centre of the lens the the principle focus is called the ….

Answer 13

Focal length

Question 14

Refraction is caused by ….

Answer 14

Waves changing speed

Question 15

A virtual image is when….

Answer 15

The rays are diverging so the light from the object appears to be coming from a completely different place.

Question 16

The ……… does most of the eyes focussing

Answer 16

Cornea

Question 17

Diverging lenses cause parallel rays of light to …..

Answer 17

Diverge (spread out)

Question 18

The axis of a line is a line….

Answer 18

Passing through the middle of the lens

Question 19

In the eye the lens ………… ……….. to focus light from objects at varying distances.

Answer 19

Changes shape

Question 20

What are the two main types of lense?

Answer 20

Converging

Diverging

Question 20

In the eye images are formed on the ………

Answer 20

Retina

Question 21

What is the unit for lens power?

Answer 21

Dioptres

Question 23

Lenses can produce ……. and ……….. images

Answer 23

Real

Virtual

Question 24

A diverging lenses shape is…..

Answer 24

Concave- caves inwards

Question 24

A real image is where…

Answer 24

The light from an object comes together to form an image on a ‘screen’- like the image formed on an eyes retina

Question 26

An diverging lens always produces a ………. image.

Answer 26

Virtual

Question 27

Magnifying glasses use …………… lenses.

Answer 27

Converging

Question 28

When you look in the mirror you see a ……….. image, as your face appears to be behind the mirror. Also in a magnifying glass as the image looks bigger.

Answer 28

Virtual

Question 29

In a diverging lens, an incident ray parallel to the axis refracts through a lens…

Answer 29

And travels in line with the principle focus (so it appears to have come from the principle focus)

Question 30

The greater the refractive index of a material used to make a lens, the ………… the lens will be

Answer 30

Flatter

Question 32

A powerful lens has a ……. focal length

Answer 32

Short

Question 33

The corneas shape is…

It has a …… refractive index

Answer 33

Convex

High

Question 34

In a converging lens, an incident ray passing through the principle focus refracts through the lens and ….

Answer 34

Travels parallel to the axis

Question 36

How does the lens in the eye change shape?

Answer 36

It is connected to ciliary muscles by suspensory ligaments.
When the muscles contract, tension is released and the lens takes on a fatter shape.
When the muscles relax the ligaments pull the lens into a thinner flatter shape.

Question 37

In a diverging lens, an incident ray passing through the lens towards the principle focus refracts through a lens and…

Answer 37

Travels parallel to the axis

Question 38

The retina is covered in ……….-…………. cells which detect ……… and send signals to the brain to be interpreted.

Answer 38

Light-sensitive

Light

Question 40

The focal length of a lens is determined by two factors: …

Answer 40

1) the refractive index of the lens material

2) the curvature of the surfaces of the lens

Question 43

What does the iris do? (Coloured part of eye)

Answer 43

It is made up of muscles that control the size of the pupil- this controls the intensity of light entering the eye

Question 47

How can you explain a virtual image?

Answer 47

“You can’t project a virtual image onto a screen”

Question 48

In laser eye surgery a laser can be used to vaporise some of the cornea to…….

Answer 48

Change its shape