Light and Vision

Question 1

Are light waves transverse or longitudinal?

Answer 1

Transverse

Question 2

What is the wavelength of a light wave?

Answer 2

The distance between two successive crests or troughs

Question 3

What is frequency of a wave?

Answer 3

The number of complete waves that pass a point in one second

Question 4

What is the velocity of a light wave? What is it dependant on?

Answer 4

How fast the wave is moving (depends on the medium it’s moving through)

Question 5

What is the speed of light in a vacuum?

Answer 5

299,800km/s (8 times around the world in one second)

Question 6

What is the range of wavelengths for radio waves?

Answer 6

1,000km-1mm

Question 7

How does magnetic resonance imaging work?

Answer 7

Hydrogen atoms absorb and emit radio waves in a magnetic field, and the changing in atom alignment creates images of the body

Question 8

What is the range of wavelengths for microwaves?

Answer 8

10cm-0.01cm

Question 9

What is the range of wavelengths for visible light?

Answer 9

700nm-400nm

Question 10

What are the types of UV light?

Answer 10

UVA, UVB, UVC

Question 11

What type of UV light is largely responsible for sunburn and eventual skin cancer?

Answer 11

UVB

Question 12

What type of UV light is mostly blocked by earth’s atmosphere and is the highest energy, most harmful to life type?

Answer 12

UVC

Question 13

What type of UV light is the lowest energy yet can still cause skin damage?

Answer 13

UVA

Question 14

How are X-Rays used to produce an X-Ray image?

Answer 14

An X-ray machine produces a concentrated beam of electrons which comes into contact with our body tissues and produces an image on a metal film

Question 15

What is the most energetic form of light/electromagnetic wave?

Answer 15

Gamma Radiation/Rays

Question 16

What are some medical uses for Gamma Radiation?

Answer 16

Sterilising medical equipment and Attacking cancer cells (in certain radio therapies)

Question 17

What is light reflection?

Answer 17

Light bouncing off a surface at the same angle it hits the surface at

Question 18

How is colour percieved?

Answer 18

When light is reflected off of certain objects, it is perceived as colour depending on the wavelength of light reflected

Question 19

What is light refraction?

Answer 19

The changing of speed and trajectory of light as it moves from one medium to another

Question 20

If light enters a denser medium, does it refract towards or away from the normal?

Answer 20

Towards the normal

Question 21

If light enters a less dense medium, does it refract towards or away from the normal?

Answer 21

Away from the normal

Question 22

What is the difference between polarised and unpolarised light?

Answer 22

Unpolarised light has electromagnetic fields oscillating in all possible directions, whereas polarised light has electromagnetic fields oscillating in only one direction

Question 23

What is the front dome of the eye called?

Answer 23

The cornea

Question 24

What is the “white” of the eye?

Answer 24

The sclera

Question 25

What is the clear tissue over the sclera?

Answer 25

The conjunctiva

Question 26

What is the liquid between the iris and the cornea?

Answer 26

The aqueous humour

Question 27

Which part of the eye changes shape to focus incoming light onto the retina?

Answer 27

The lens

Question 28

The eye behind the lens is filled with what? What is the difference in this substance between younger and older individuals?

Answer 28

Filled with the vitreous humour, which is more jelly-like at younger ages and more liquid-like in older individuals

Question 29

Which part of the eye contains light receptive cells?

Answer 29

The retina

Question 30

What layer is located between the sclera and the retina and supplies blood to the retina?

Answer 30

The choroid

Question 31

What transmits the signals from the retina to the brain?

Answer 31

The optic nerve

Question 32

What is the term for long-sightedness? Are people with long-sightedness better at seeing near or distant objects?

Answer 32

Hyperopia People with hyperopia are better at seeing distant objects, while near objects appear blurry or cause eye strain

Question 33

Where is the focal point of incoming light focused in hyperopic eyes? What type of lenses are used to correct this?

Answer 33

Behind the retina due to a short axial (front to back) left. Convex (+ve power) lenses are used to pull the focal point towards the front of the eye to focus it on the retina

Question 34

What is the term for short-sightedness? Are people with short-sightedness better at seeing near or distant objects?

Answer 34

Myopia People with myopia are better at seeing close objects, while distant objects appear blurry or cause eye strain

Question 35

Where is the focal point of incoming light focused in myopic eyes? What type of lenses are used to correct this?

Answer 35

In front of the retina to a long axial (front to back) length. Concave (-ve power) lenses are used to push the focal point towards the back of the eye to focus it on the retina

Question 36

What are some different types of blindness

Answer 36

``` Corneal opacity (translucency of the cornea caused by trauma, infection or disease) Cataract (Lens opacity caused by ageing or trauma) Retinal detachment (Separation of the retinal layer from the choroid) Visual Tract (Problems with transmission of signal through the optic nerve) ```

Question 37

What is the purpose of the pinhole test?

Answer 37

Looking through a pinhole removes peripheral beams of light, which should improve hyperopic or myopic issues with the eye. If it doesn't improve, it could be a neural issue.