Optics Science review

reflection

light hitting something and the rays ‘bouncing’ reflecting back to our eyes

What are the two important parts of glass? What is their purpose?

light rays pass through the front transparent glass and then hit the reflection layer (silver/aluminum) behind it, causing the rays to bounce back to our eyes (causes us to see the reflection)

Light Ray

electromagnetic waves - carry energy / travels

explain how light rays travel and transferrs

electromagnetic waves - carry energy / travels through a vaccum

light energy transferred through radiation

(transfer of heat) what is the difference between conduction and convection? give examples

conduction: direct contact with solids - transfer between adjacent molecules

ex. heating a pan on a stove

convection: movement of a fluid when heated fluid is caused to move away from heat source - carrying energy happens because of density (liquid heated > rises >cools > falls)

ex. lava lamps, burning paper, cooking beans in liquid,

(transfer of heat) what is radiation?

no physical contact - energy coming off of a source - travels through space at speed of light

ex. heating hands near a fire

types of light emissions

Luminous: an object that emits/produces its own light (eg. sun)

Non-luminous: an object that does not produce its own light and is visible due to reflected light (eg. a tree)

Geometric Optics

light rays to determine how light behaves when hitting objects

give an example of transparent, translucent, and opaque

transparent: air, water, clear glass

translucent: thin paper, vegetable oil

opaque: wood, concrete, floors

(model of light)

What are the 2 rays and line? Define all of them

**Normal:** line __perpendicular__ to where ray of light meets

**Incident ray (ray coming in):** ray traveling from __source to surface__

**reflected ray (ray bouncing off)**: begins at point where __incident ray + normal__ meets

(model of light)

What are the two angles? Define all of them

angle of **incidence**: between normal and __incident__ ray

angle of **reflection**: between normal and __reflected__ ray

What is **specular** reaction and **diffuse** reaction?

**specular**: All angles of incident for light rays identical (light hits SMOOTH surface) - all angles of reflection identical

**diffuse**: When parallel incident rays are reflected off of an IRREGULAR surface - all angles of reflection different

Name all the ways of production of light. what are the ones that are natural and the ones that are man-made?

**NATURAL**: Bioluinescence, trioluminescence

**MAN-MADE:** luminous, incondescene, electric discharge, phosphorescence, fluorescence, LED, Chemillumiescence,

What are the two laws in Ray Model of Light?

• incident ray, reflection ray, normal to the surface of the mirror - lie on same plane

• angle of reflection = angle of incidence

What are the similarities and differences of Phosphorus and Fluorescent light?

* both result from absorption of ultraviolet light

**Phosphorus** : - emission over period of time

**fluorescent** : - __IMMEDIETE__ emission of visible light

MEDIUM

physical substance through which energy is transferred (convection / conduction)

explain LANTA

* wave length - the distance waves travel within a period

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from L → R: Lanta gets shorter

what is electromagnetic spectrum?

light listed according to diff energy levels

what did maxwell predict about electromagnetic waves?

Electricity + magnesium work together - forms a chain travelling through space

the resulting electromagnetic waves doesn’t require a medium for transmission - travels speed of light

Why is studying electromagnetic waves better than studying only visible light?

Most things in the universe aren’t in the electromagnetic range to be visible to us (radio waves, microwave, TV)

bioluminescence and triboluminescence - Give examples

**bioluminescence** : produced in living creatures

**triboluminescence** : light emitted because of friction with minerals / crystals

Does fluorescent brighteners in cleaners make clothes cleaner? explain

fluorescent brighteners in cleaners do not make clothes cleaner

* the brighteners absorb UV light, producing visible light and making clothes brighter

What are some problems and dangers with fluorescent lights?

fluorescent light contains mercury (non-biodegradable)

Why are incandescent bulbs ineffective? Why are fluorescent bulbs better?

Incandescent bulbs are ineffective because they are constantly at a high temperature in order to produce light - it cannot be on for a long time or else it will overheat - can’t produce that much electricity / uses more energy + less reliable

Why are LED lights more effective than fluorescent bulbs?

LED lights use a majority of their energy focused on producing light (not much energy wasted and therefore can last longer) - unlike fluorescent bulbs, it has no mercury, so more biodegradable.

How do fluorescent lights work? What is inside it? What happens when it is turned on?

• both electric discharge and fluorescence

• tube filled with mercury vapour - emits UV light

• tube has fluorescent inner surface

when on:

• electric current causes mercury to emit UV light

• UV hits fluorescent inner surface - produces visible light

How do you make light using electric discharge?

passing an electric current through a gas → causes gas to GLOW

(ex. neon sign)

What si luminous and non-luminous light

Drawing Ray Diagrams for Concave Mirrors (diagrams)

(1): Locate the **Principal Axis** \n (2): Locate the Centre of Curvature "**C**" \n (3): Locate the **Vertex** \n (4): Locate the Focal Point/Focus (**F**) - half the distance of the radius, half way __between the Centre of Curvature and the Vertex.__ \n (5): Determine the Focal __length__ (**f**) - distance between the vertex and the focal point

what does SALT stand for (give examples)

S- size (small,large,same)

A- attitude (up,invert)

L- location (behind mirror, betwn C-F, etc)

T- type (virtual, real)

(Concave mirrors-SALT) How do you describe an object when it is

\-BEYOND C

S- Smaller

A- Inverted

L - Between C & F

T - Real

(Concave mirrors-SALT) How do you describe an object when it is

\-On C

S- Same size

A- Inverted

L - on C

T - Real

(Concave mirrors-SALT) How do you describe an object when it is

\-Between C and F

S- bigger

A- Inverted

L - beyond C

T - Real

(Concave mirrors-SALT) How do you describe an object when it is

\-on the FOCAL POINT

NO IMAGE

(Concave mirrors-SALT) How do you describe an object when it is

\-Object between F and MIRROR

S- bigger

A- upright

L - behind the mirror

T - Virtual

(concave) What happens with the light rays when the object is Beyond C, At C, or between C-F

1 - incident rays that travel perpendicular to the principal axis reflect off mirror - reflective rays go through FOCUS

2- incident ray travel through focus - reflective rays parallel to principal axis

-all real all inverted

(concave) What happens with the light rays when the object is AT **F**

NO IMG

(concave) What happens with the light rays when the object is betwn F and Mirror

S- bigger

A- upright

L - behind the mirror

T - Virtual

what is the relationship between TYPE and ATTITUDE of an image

**Real** - Inverted

**Virtual** - Upright

what is the difference between PLANE, CONCAVE and CONVEX mirrors

PLANE: - virtual imgs - reflected image same size

CONCAVE: - reflective rays converge on a point - reflected image magnified

CONVEX: - light rays DIVERGE - virtual imgs - reflected image smaller

list these electromagnetic waves from **lowest to highest energy :**

microwaves, gamma rays, infrared light, visible (white) light, radio waves, X-ray

radio waves < microwaves < infrared < visible (white) < ultraviolet < x-ray < gamma ray

SALT for Plane mirrors

S - same size

A - inverted

L - behind mirror

T - virtual

ray diagram for convex mirror (and attributes)

S- smaller

A- upright

L- between F-V(mirror)

T- virtual

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7 distinct colours in order of lowest to highest energy

Red \n Orange \n Yellow \n Green \n Blue \n Indigo \n Violet