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Optics > Production And Reflection Of Light > Flashcards

Production And Reflection Of Light Flashcards

0
Q

What does light act like?

A

A particle, called a photon, or a wave

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1
Q

What is light?

A

A visible form of energy

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2
Q

What is a photon?

A

A bundle of energy

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3
Q

What are the properties of electromagnetic waves?

A

Both require electric and magnetic, requires no medium to be transmitted, travel at speed of light, distinguished by their energy or frequency to form the electromagnetic spectrum

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4
Q

What is the electromagnetic spectrum?

A

Radio, microwave, infrared, visible light, u.v., x Rays, gamma rays

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5
Q

As the energy increases so does the…

A

Frequency, so shorter waves

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6
Q

What are the properties of light?

A

Travels very fast, travels in straight lines “rectilinear propagation”, can reflect be absorbed or bend whenever it goes from one medium into another

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7
Q

What are the colours associated with visible light?

A

ROYGBIV, red, orange, yellow, green, blue, indigo, violet

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8
Q

What are the two sources of light?

A

Luminous, and non-luminous

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9
Q

Name the different luminous sources

A

Incandescent, electric discharge, phosphorescence, fluorescence, chemiluminescence, bioluminescence, triboluminescence, light emitting diodes

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10
Q

Explain incandescent light

A

Light produced by high temperatures, as temp rises colour of light changes from red to blue-white. Inefficient

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11
Q

Explain electric discharge

A

Light produced by passing electric current through a gas. Different gases produce different colours, e.g. Neon gas- red, Mercury- blue

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12
Q

Explain phosphorescence

A

Special materials called phosphors absorb ultraviolet light and then emit visible light later over a period of time

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13
Q

Explain fluorescence

A

Fluorescence materials absorb u.v. Light and immediately release it as visible light

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14
Q

Explain fluorescent lights

A

Mercury gas produces u.v. Light by electric discharge, visible light is created by fluorescence. Much more efficient but has toxic waste, CFL used to replace bulbs

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15
Q

Explain Chemiluminescence

A

Also called cold light, light produced by a chemical reaction, inexpensive, no electricity required

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16
Q

Explain bioluminescence

A

Chemiluminescence which occurs in living things

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17
Q

Explain Triboluminescence

A

Production of light by scratching, rubbing, or crushing of crystals

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18
Q

Explain LEDS

A

Electronic device which emits light by having current go in one direction using a semi-conductor, no filament, no heat, very efficient, replacing incandescence and fluorescent lights

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19
Q

What are the two types of reflection?

A

Specular reflection (off smooth surface) and Diffuse reflection (of rough surface)

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20
Q

What is the Ray model of light?

A

Used to study how light behaves when it strikes objects or travels into other materials, where a ray is represents using a straight line, and a beam represents a bundle of Rays

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21
Q

What are the three possible states of beams?

A

Converging, diverging, parallel

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22
Q

In a mirror what is the object and image?

A

The object is the actual thing and source of light,whereas the image is a reproduction of an object through the use of optic devices

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23
Q

Where is the image in a plane mirror?

A

The image is where the reflected Rays appear to meet or converge

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24
Q

What are the image characteristics?

A

Size, Attitude, Location, Type

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25
Q

What are the three types of curved mirrors?

A

Spherical, cylindrical, parabolic

26
Q

What happens if Rays are emitted from the focus of a converging mirror, or if Rays are pointing at the focus of a diverging mirror?

A

The reflected Rays will be parallel to the principal axis

27
Q

What is spherical aberration?

A

In reality Rays reflecting off a spherical mirror do not all meet at the same point

28
Q

Explain images for converging mirrors

A

Real images always inverted, virtual images always upright, if object is beyond F, real images occur, size depends on the object location. If the object is closer that F, images are virtual and larger than the object. If the object is at F there is no image since reflected Rays are parallel

29
Q

Explain the concept of two regions in converging mirrors

A

There are two regions, between F and C, and beyond C. Image and object are never in the same region, whichever is beyond C will be bigger in size

30
Q

Explain images for diverging mirrors

A

Always virtual, upright, smaller than object, and slightly closer to mirror than the object

31
Q

What is refraction?

A

Changing direction of lights as it passes from one medium into another in which the speed of light changes

32
Q

What are the two requirements for refraction?

A

Angle of incidence larger than 0, and speed of light must change between the two mediums

33
Q

What happens it speeds up or slows down?

A

Speeds up- away from the normal, slows down- towards the normal

34
Q

What medium is light the fastest?

A

Vacuum or air

35
Q

What is partial reflection or partial refraction?

A

When light goes from one medium into another, part of it reflects and part of it refracts

36
Q

What is the index of refraction?

A

Is the ratio between the speed of light in air to the speed of light in the medium, or mathematically n=c/v

37
Q

What is snells law?

A

In 1621 Snell discover relationship between angle of incidence and angle of refraction. sin(i)/sin(R) = c/v = n

38
Q

What is Snells General law?

A

n1sin(theta1) = n2sin(theta2)

39
Q

What are the two conditions for total internal reflection to occur?

A

Light travels into a faster medium to bend away from the normal, and the angle of incidence is greater than the critical angle

40
Q

The bigger the difference in the indices of refraction of the two media the ___ the critical angle

A

Smaller

41
Q

The smaller the critical angle the greater the _______

A

Internal reflection

42
Q

What is the critical angle?

A

The angle of incidence in which the angle of refraction is 90 degrees

43
Q

Explain the brilliance of diamonds

A

Diamonds have a very small critical angle due to its large index of refraction. As well diamonds are cut so that most light strikes the sides of the diamond so that i> critical angle, causing the light to be reflected internally and come out the top of the diamond

44
Q

Explain fibre optics and three applications

A

Plastic (lucite) and our glass fibres with small critical angles reflect light internally, acting like wires which carry light instead of electricity. For transmitting information, internal examinations, and interesting lights

45
Q

Explain Triangular prisms

A

The critical angle of glass is about 41 degrees, and the prisms are cut at 45 degree angles. Therefore any incoming light will experience total internal reflection. Prisms used when we want to minimize loss of light.

46
Q

Explain retro reflectors

A

A retro reflector acts like to prisms together and reflects light straight back, except it does in all directions. It is in the shape of a corner of a cube.

47
Q

Explain apparent depth

A

Objects appear to be closer or shallower due to refraction of light, occurring when you look into a MORE refractive medium. To calculate, d’ = n2/n1* d

48
Q

Explain apparent height

A

From under water things above look like they are farther away. Happens when you are looking into a less refractive medium.

49
Q

Explain a mirage

A

An image formed by refraction and total internal reflection due to differences in air temperature. A TO B: as light goes from cold to hot air it speeds up, therefore bends away from the normal. AT B: eventually we get total internal reflection, and light goes back up. B TO C: as light goes from hot to cold air it slows down, therefore bends towards normal

50
Q

Explain a reverse mirage

A

Occurs if not air is above cold air

51
Q

Explain shimmering

A

At night air above lake is colder than air near lake, therefore you get images of moon on lake

52
Q

Explain Rainbows and the three requirements

A

Due to dispersion and total internal reflection of light in water droplets. Needs millions of droplets, sun is behind you, and rainbow is at 42 degrees to observer

53
Q

What is dispersion?

A

Separation of whit light into various colours due to the different refraction of each colour due to different speeds of each colour.

54
Q

What does the retina in the eye do?

A

Closes and opens around a central hole called pupil to let in less or more light. It is the coloured part of the eye.

55
Q

What does the lens and cornea in the eye do?

A

Structures in the eye that causes light to converge . Cornea is transparent layer on top of pupil, and light is refracted more through the cornea than lens.

56
Q

Explain light sensitive cells in the eye

A

Light sensitive cells are in the retina at the back of the eye cavity, converting light signals into electrical signals that are then transmitted to the brain from the optic nerve

57
Q

Explain the blind spot

A

We have a blind spot as the optical nerve is located at the back of the eye and so there are no light sensitive cells at that spot. Each eye compensates for the others blind spot

58
Q

How does the eye focus on images?

A

Eye muscles called ciliary muscles help the eye focus by slightly changing the shape of the eye lens. This change of shape of the eye lens changes the focal length of the lens to slow focusing of the image on the retina, process called accommodation

59
Q

What is hyperopia

A

Also known as far sightedness, person has difficulty seeing close, occurs because distance between lens and retina too small or cornea lens combo too weak, causing light to focus behind the retina. Corrected with a converging lens, called positive meniscus

60
Q

What is presbyopia?

A

Age related form of hyperopia, corrected with converging lens

61
Q

What is myopia?

A

Also known as near sightedness, trouble seeing far because distance between lens and retina too large or cornea lens combo too strong so light focuses before the retina. Corrected with a diverging lens, called a negative meniscus

62
Q

Explain contact lenses

A

Lens placed directly in cornea of eye,

Can correct both hyperopia and myopia, and can also be used for strict,y cosmetic purposes

Optics (1 decks)

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