Unit 2 - Optics and Light (Part 1)

Question 1

A few light characteristics include:

Answer 1

• Light travels in straight lines
• Does not require a medium
• Light is a type of electromagnetic wave
• Light is transferred through a process called radiation

Question 2

Medium -

Answer 2

Any physical substance through which energy can be transferred

Question 3

Radiation -

Answer 3

A method of energy transfer that does not require a medium; the energy travels at the speed of light

Question 4

Electromagnetic wave -

Answer 4

A wave that has both electric and magnetic parts, does not require a medium, and travels at the speed of light

Question 5

Visible light -

Answer 5

Electromagnetic waves that the human eye can detect

Question 6

What is the order of the electromagnetic spectrum from left to right?

Answer 6

Radio waves, microwaves, infrared light, visible light, ultraviolet light, X-ray, gamma rays

Question 7

Examples of radio waves:

Answer 7

• cell phones

- tv signals

Question 8

Examples of microwaves:

Answer 8

• microwave oven

- telecommuications

Question 9

Examples of infrared light:

Answer 9

• remote control

- food warmers

Question 10

Examples of visible light:

Answer 10

• visible laser

- human vision

Question 11

Examples of ultraviolet light:

Answer 11

• causes sunburns

- water disinfectants

Question 12

Examples of X-rays:

Answer 12

• metal imaging

- astronomy

Question 13

Examples of gamma rays:

Answer 13

• cancer treatments

Question 14

Visible spectrum -

Answer 14

The continuous sequence of colours that make up white light

Question 15

Incandescence -

Answer 15

The production of light as a result of high temperature (eg. incandescent lightbulbs, stove) Type of energy transformation: various sources, heat energy, light

Question 16

Electric discharge –

Answer 16

The process of producing light by passing an electric current through a gas (eg. Lightning, lit neon sign) Type of energy transformation: Electric energy, light energy

Question 17

Phosphorescence -

Answer 17

The process of producing light by the absorption of ultraviolet light resulting in the emission of visible light over an extended period of time (eg. Glow-in-the-dark toys) Type of energy transformation: ultraviolet light, visible light (delayed)

Question 18

Florescence –

Answer 18

The immediate emission of visible light as a result of the absorption of ultraviolet light (eg. Fluorescent light, highlighter) Type of energy transformation: ultraviolet light, visible light (right away)

Question 19

Chemiluminescence -

Answer 19

The direct production of light as the result of a chemical reaction with little/no heat (eg. Glow stick) Type of energy transformation: Chemical energy, light energy

Question 20

Bioluminescence –

Answer 20

The production of light in living organisms as the result of a chemical reaction with little/no heat (eg. Firefly, living organisms) Type of energy transformation: Energy, light

Question 21

Triboluminescence –

Answer 21

The production of light from friction as a result of scratching, crushing, or rubbing certain materials (eg. Rubbing 2 quartz crystals together)

Question 22

LED -

Answer 22

Light produced as a result of an electric current flowing in semiconductors (eg. Christmas lights) Type of energy transformation: Electric energy, light energy

Question 23

Luminous object –

Answer 23

Produces its own light (eg. Flashlight, candle, sun)

Question 24

Non-luminous object –

Answer 24

Does not produce light, but it can reflect light from other sources (eg. Pencil, book, moon)

Question 25

Geometric optics:

Answer 25

The use of light rays to determine how light behaves when it strikes objects

Question 26

Image –

Answer 26

A reproduction of an object through the use of light

Question 27

What are the 5 scientific symbols for a plane mirror?

Answer 27

``` I = incident ray Øi = angle of incedence N = the normal R = reflected ray Ør = angle of reflection ```

Question 28

Laws of reflection:

Answer 28

1. The angle of incedence = angle of reflection | 2. The incident ray, reflected ray and the normal line all lie in the same place

Question 29

Specular reflection:

Answer 29

Reflection of light off a smooth surface where incident and reflected rays are parallel

Question 30

Diffuse reflection:

Answer 30

Reflection of light off an irregular or dull surface where incident rays are parallel but, reflected rays are not (appear scattered)

Question 31

Real image:

Answer 31

Rays of light come together to make an image

Question 32

Virtual image:

Answer 32

No rays of light at image location, it only appears that rays of light come from the image

Question 33

Salt

Answer 33

Size of image (is the image bigger/smaller/same size as the object? Also can be measured)

Question 34

sAlt

Answer 34

Attitude (is the image upright/right or inverted/upside down compared to the object)

Question 35

saLt

Answer 35

Location (where is the image in relation to the object and the mirror/lens? Eg. Same or opposite side/how far? )

Question 36

salT

Answer 36

Type (is the image real or virtual)

Question 37

Describe which end of the electromagnetic spectrum has more energy:

Answer 37

The further right down the electromagnetic spectrum, the more energy the colours are. Eg. Blue has more energy than orange

Question 38

Locations images in a plane mirror:

Answer 38

1. Images and plane mirrors are located at the point where the backward extensions of reflected rays intersect 2. The image is the same size as the actual object, image is upright but reversed, image appears behind the mirror, equal distance from the mirrors as the object, images is virtual 3. Two ways to locate the image

Question 39

Centre of curvature –

Answer 39

The centre of the sphere whose surface has been used to make the mirror

Question 40

Principal axis –

Answer 40

The line through the centre of curvature to the midpoint of the mirror

Question 41

Vertex –

Answer 41

The point where the principal axis meets the mirror

Question 42

Focus -

Answer 42

The point at which light rays are parallel to the principal axis, and converge when they are reflected off a converge mirror

Question 43

List some differences between virtual and real images:

Answer 43

* Real images appear inverted, virtual images appear right * Real images can be obtained on a screen, virtual images cannot be seen on a screen * In case of mirrors, real image lies in front while virtual image lies behind the mirror * In case of lenses, real image lies on the other side of the object whereas virtual image lies on the same side of the object

Question 44

Refraction -

Answer 44

When light hits an object and it is refracted, this means light goes through it, but is bent

Question 45

Reflection -

Answer 45

When light hits an object it can be reflected, meaning light bounces back

Question 46

Absorbed -

Answer 46

When light hits an object and it is absorbed, light is "taken in" and converted to other energy types

Question 47

Concave mirror –

Answer 47

A mirror with a curved reflecting surface, concave means the mirror is bulging inward (converging)

Question 48

Convex mirror –

Answer 48

A mirror with a curved reflecting surface. Convex means the mirror is bulging outwards (diverging)