Science final grade 8 study guide!

Science final study guide

natural light source

light made naturally

Artificial light source

Made by man

Incandescent

Produces light from high heat temperatures

Fluorescent

Electric light formed in tube shape and light being produced on inside by mercury Vapor and phosphor coating

chemiluminescence

Light coming from a chemical reaction

Bioluminescence

A light produced by nature; natural

Transparent

When an object lets all light through

Translucent

When light partially passes through

Opaque

• When no light passes through

• Light is absorbed

Incident ray

The light ray hitting the reflective surface

Reflected ray

The light ray being reflected of the reflective surface

The normal

Imaginary line of the middle

Plane mirror

Flat reflective surface

Light form

• energy

• electromagnetic radiation

light particle

photon

visible light spectrum

on the electromagnetic spectrum

longer wavelength vs shorter wavelength

• longer wavelength - less energy

• shorter wavelength - more energy

photoelectric effect

where you see light as a particle

double slit experiment

shows light is a wave

Reflection

• When a light ray bounces off an object

• Law of reflection - reflection off a smooth surface must have an angle of a reflection equal to the angle of incidence

Refraction

• when light changes direction when passing though an object

• When light hits the substance it slows down, drifts, then when out of the substance, it changes direction

• Denser material → bends towards the normal

• Less dense material → further from the normal

Light transmission

• light passes through all the way

• Ex: a window

Light absorption

• when light doesn’t pass through

• Ex: a desk

Concave mirror

• Concave mirror - reflects inward and upside down

• Ex: telescope

Concave lens

• reflects outward

• Used for glasses lens for people with myopia; nearsightedness

Convex mirror

• reflects outward and image appears smaller

• Ex: security mirrors

Convex lens

• Reflects inward towards the focal point

• Used for people with hyperopia; farsightedness

parts of the eye

• Cornea

• Retina

• Lens

• Optic nerve

• Cones

• Rods

• Aqueous Humor

• Pupil

• Iris

• Sclera

• Ciliary muscle

• Virtuous Humor

Real image vs virtual image

• Real image - when rays converge

• Virtual image - when rays diverge

examples of vision enhancing technologies

• laser eye surgery

• Glasses

• VR

Class 1, 2, 3 lever

• C1 - fulcrum in middle

• C2 - fulcrum on left

• C3 - fulcrum on right

Effort force

• Force applied to machine

• the force we apply to move the object (input force)

Load force

the object that is trying to be moved

effort arm

Where effort is applied (the input force)

Load arm

The arm that carries the load

Mechanical advantage (MA)

Ratio of input force to output force

Inclined plane

A slope, mainly to push objects down

Work

The amount of work being done to an object, what force has caused it to do

Work input

Amount of energy put into the machine

Work output

The work that was done by a machine

Wheel and axle

A wheel that spins around an axle

Gear

Turn force to motion

Gear train

2 or more gears working together

Chain and sprocket

Chain that hooks into the teeth of the gears and moves them

Driven gear vs driving gear

• Driven - the front gear

• Driving - the last gear

Speed ratio

• ratio of output speed to input speed

• Greater than one - driven gear slower than driving gear, increasing torque (rotation) but reducing speed

• Equal to one - spins at equal speeds

• Less than one - gears turn faster, less torque more speed

Fixed pulley

Rope attached to fixed point

Movable pulley

Free to move up or down

Compound pulley

Fixed and movable pulley

Potential Energy

The energy that is stored

Kinetic energy

Energy made by motion

Energy transmission

same type of energy moves from one object to another

Energy conversion

energy switches to different type in same object

Efficiency

• how much energy from machine was transferred to load

• stated as percent

• higher efficiency, better at transferring energy

• never a completely efficient machine because there is a loss of energy

Friction

Force that stops motion when in contact with two surfaces

Complex machine

Made of two or more simple machines

subsystems

System that are apart of a larger system

Greater than 1

Force advantage

Less than 1

Speed advantage

Equal to one

No advantage of moved direction to effort

Work formula

• W = F x D

• Measured in joules

Ramp and lifting straight up equal work

More distance is needed while using a ramp

Water quality

Condition and characteristics of water

Ground water

Water that is stored underground

Salinity

The amount of salt found in the water

Erosion

Weather displaces sediments

Ocean basins

The largest depression in earth

glaciation

land is covered by glaciers

El Nino and la nina

El Nino - when ocean temperatures rise

La Niña - ocean temperatures cooling

Phosphates

Chemical compound that contains phosphorus

water distribution

drinking water that comes from plant goes to taps

potable

water that is safe to consume

osmosis

low concentration to a high concentration

deposition

laying down sediments through weather

sea wall

wall to protect shore from erosion

currents

movement of seawater by gravity, winds, and water density

turbidity

water quality of being cloudy, thick, or opaque

evaporation

when liquid gets turned into vapor; liquid to gas

reverse osmosis

forcing salty or brackish water through a semipermeable membrane by applying pressure, leaving solutes on one side of the membrane

flow rate

how fast a liquid flows

gulf stream

• ocean water has more thermal energy then atmosphere

• thermal energy transfers to air

sediment

solid material that is moved and moved to new location

dissolved oxygen

oxygen that is in water

upwelling

when cold nutrient water is pushed to the top of the ocean

Ocean formation

• coastline

• Continental shelf

• Continental slope

• Continental slide

• Abyssal plain

• Oceanic trench

• Volcanic island

Two main factors that impact ocean currents

• salinity

• Temperature

Increased temperature and salinity

• increased temperature expands water slightly, making it dense and causes upwelling to happen

• Increased salinity increases density by the amount of salt dissolved in water

Currents

Move heat, nutrients, and oxygen around ocean

Waves and tides

• surface waves caused by wind

• Visible flow of energy

• Tides because of moons gravitational pull

Glaciers

• erratics proves glaciers move over time

• Form in a cirque

• Form terminal or lateral moraines

• Creation of wide valleys (U shaped)

Stream and river characteristics

• intermediate, small, and fine types of sediments

• Erosion can cause rivers to form into a new shape

Fresh water solutions

• distillation - salt water turned into fresh water

• Reverse osmosis- forcing salty or brackish water through semipermeable membrane by applying pressure, leaving solutes on one side, and the other has fresh water

Environmental challenges for marine organisms

• temperature

• Water movement

• Water pressure

• Light

• Salinity