HEALTH Light And Sight

Question 0

What is refraction?

Answer 0

The bending of light/change of speed as it passes from one material to another.

Question 1

Light is focused by the ____ and the _____. Most of the refraction takes place at the _____. The ____ changes shape and allows the eye focus on objects at different distances.

Answer 1

Light is focused by the CORNEA and the LENS. Most of the refraction takes place at the CORNEA. The LENS changes shape and allows the eye focus on objects at different distances.

Question 2

When light passes from air into glass, light bends _____ the normal and when it passes from glass to air it bends _____ from the normal.

Answer 2

When light passes from air into glass, light bends TOWARDS the normal and when it passes from glass to air it bends AWAY the normal.

Question 3

Concave

Answer 3

Bends in

Question 4

Convex

Answer 4

Bends out

Question 5

How do convex affect light?

Answer 5

Brings the light to a fous

Question 6

How does concave lens affect light?

Answer 6

Spreads it out

Question 7

How is the image formed on the retina different to the real object?

Answer 7

Image is formed upside down, back to front and smaller

Question 8

What is focal length?

Answer 8

The distance between a lens and the point where parallel rays of light are brought to a focus.

Question 9

Describe an experiment to measure focal length

Answer 9

Put e lens i front of a screen and move e lens until a sharp image if distance object is obtained on the screen. Measure the distance from the lens to the screen and this is the focal length,

Question 10

Short sighted people can’t focus on _____ objects clearly.

Answer 10

Distant

Question 11

Long sighted people can’t focus on _____ objects clearly.

Answer 11

Close

Question 12

What type of lens corrects short sighted vision?

Answer 12

Concave

Question 13

What type of lens corrects long sighted vision?

Answer 13

Convex

Question 14

What type of light do fibre optic transmit?

Answer 14

Cold light (no heat is transmitted)

Question 15

What is angle of incidence?

Answer 15

Angle between ray and normal.

Question 16

What is the angle of refraction?

Answer 16

Angle between refracted ray and normal.

Question 17

What is the normal?

Answer 17

The perpendicular line that passes thought the angle of incidence and angle of refraction.

Question 18

What is short sighted in terms of light rays?

Answer 18

Light rays are brought to a focus before the retina.

Question 19

How would a concave lens help to fix short sighted ness?

Answer 19

Would spread rays out so that they focus on retinia

Question 20

What is long sighted in terms of light rays?

Answer 20

Light rays brought to a focus behind the retina.

Question 21

Why would a convex lens solve long sighted ness.

Answer 21

Convex lenses converge the rays so that they focus on the retina.

Question 22

What is the unit of measurement for the power of a lens?

Answer 22

Dioptres.

Question 23

What is focal length measured in?

Answer 23

Meters

Question 24

_____ lenses have a positive power (+) | _____ lenses have a negative power (-)

Answer 24

Convex lenses have a positive power (+) | Concave lenses have a negative power (-)

Question 25

What are optic fibres used for?

Answer 25

To see inside a patients body without surgery.

Question 26

What are optic fibres used for? (The appliance)

Answer 26

Endescope

Question 27

Explain how an endoscope works

Answer 27

One bundle of fibres carry the cold light into the patient. The second bundle of light brings this reflected flight back to the surgeon's eye. the bundles are flexible so can move around inside the patient.

Question 28

Is the angle of incidence less or more an the angle of refraction?

Answer 28

Less

Question 29

Does a thin lens or thick lens have a longer focal length?

Answer 29

Thin

Question 30

How does the eye focus on ne'er and distant objects?

Answer 30

The lens changes shape. For example to view near objects the muscles change the lens shape to thick.

Question 31

What are the advantages if endescopes?

Answer 31

Cold light sources and small incision means faster recovery.