Physics Part 2

Fluoresencece

Light is emitted when a substance is exposed to electromagnetic radiation. EXAMPLE : Light bulb

Phospherence

The ability to absorb energy from another source of light and then slowly emit it over a long period of time. EXAMPLE: Glow in the dark

Incandescence

Light that is produced by an object, such as a metal, that is at a very high temperature. EXAMPLE: Light bulb

Electric Discharge

Light is produced when a electric current passes through the air or passes through a gas like neon EXAMPLE: Street signs

Bioluminescence

Light is produced by a plant or animal. EXAMPLE: Angler Fish

Triboluminescence

Light produced from friction when crystals are rubbed or crushed. EXAMPLE: Sugar crystal

How does a glow stick produce chemiluminescence

• A glow stick is separated by a glass vial until you are ready to use

• When you bend it, the glass breaks, which allows the two chemicals to mix together

• The mixture causes a chemical reaction that makes the liquid glow.

Telescope - Types of Lens, Size, Type, Orientation

• Converging and Diverging

• Larger

• Virtual

• Inverted

Magnifying glass

• Converging

• Larger

• Virtual

• Upright

Camera - Types of Lens, Size, Type, Orientation

• Converging

• Larger

• Real

• Inverted

Projector - Types of Lens, Size, Type, Orientation

• Converging

• Larger

• Real

• Inverted

A?

Iris

B?

Cornea

C

Pupil

D

Lens

E

Vitreous Humor

F

Sclera

G

optic nerve

H

Blood Vessels

I

Retina

Iris

Automatically controls how much light enters the eye

Cornea

Eyes outermost lens to focus incoming light and serving as a shielf against dirt, germs and harmful UV rays

Pupil

Adjustable that controls the amount of light entering the eye

Lens

To bend and focus incoming light rays precisely onto the retina to create clear, sharp images

Retina

Convert light into electrical signals and sends them to the frame which translates those signals into the images you see

Vitreuos Humor

Jelly. Maintains the eyes round shape

Sclera

Acts as a protective shield for the internal eye tisse

Optic Nerve

Carries visual information from your eyes to your brain

Blood Vessels

Delievers oxygen and essential nutrients to support metabolic demands

Do you see with your eyes?

No. We “see” with our brain. The eye just transfers information to the brain

Hyperopia

• Far sighted

• No diffuclty seeing distant objects

• Light from all nearby objects focuses behind the retina

Myopia

• Near sighted

• No difficulty seeing nearby objects

• Light from distant objects is brought to focus in front of the retina

Where does light bend when entering a denser medium

Closer to medium

Where does light bend when entering a less dense medium

Further from the normal

What is n. in n=c/v

Index of refraction

What is c. in n=c/v

Constant. Speed of light in vaccum. 3.00×10⁸

Apparent Depth

• Our brain automatically assume that light always travel in a perfectly straight line

• Your brain traces the incoming light rays straight backward into the water instead of following the bend

Mirage

• On a sunny day, the asphalt gets hot, it warms the layer of air just above it so the cool air sits on top of a layer of very hot air

• As light from the sky travels down through the cool air and hits the hotter air, it begins to bend. Hot air has a lower index of refraction so the light bends so sharp that it goes through total internal reflection which means its bouncing back up toward your eyes like a mirror

Total Internal Reflection

• The angle of refraction is always larger than the angle of incidence

• If you increase the angle of incidence past the critical angle, it will reflect back into the medium.

• In other words, there is no refracted ray, only a reflected ray

For example, critical angle is 48.8 but the incident angle is 60.

Conditons of total internal reflection

1. Light is travelling more slowly in the first medium than in the second

2. The angle of incidence is large enough that no refraction occurs in the second medium. Instead the rat is reflected back into the first medium.

Dispersion

White light separating into continuous sequence of colours in a glass prism

• Each colour of visible light travels at slightly different speeds

• Violet light slows down more than red light when entering the prism

• Violet light is being refracted more than any other colour.

Converging Lens (convex)

• Type of lense that is widest at the center

• Example : magnifying glass, camera, reading glasses

Diverging Lens (concave)

• Type of lens that is the narrowest in the middle

• Example: Eye glasses, telespcope

Refraction in Lenses

Light rays gets refracted two times. Once when entering the lense and another when leaving the lense