Science Final Exam

Waves

oscillations that carry energy and information from one place to another

Transverse Waves

has its oscillations perpendicular to the direction of the wave

Transverse Waves Move

left to right

Transverse Waves’ Oscillations move

up and down

Longitudinal Wave

has oscillations in the same direction the waves move

Frequency

a measure of how often it goes up and down

Frequency Measure

Hz

Amplitude

the height of the wave above the level surface

Wavelength

length of one complete cycle of a wave

Wavelength measured by

crest to crest, or trough to trough

Wavelength Measure

meters

Compression

when all the waves are close together

Rarefaction

when the waves are spread out

Speed

describes how fast the wave moves

Reflection

waves bounce off and go in a new direction

Refraction

wave bends as it crosses the edge (changes mediums/ materials)

Diffraction

bends as it goes around a corner or through an opening (not changing mediums/ materials)

Absorption

amplitude gets smaller and smaller as it passes through the material

Circular Waves

move out in all directions

Plane Waves

move forward in one geometric plane

Constructive Waves

two waves combine to make bigger

Destructive Waves

two waves combine to destroy

Sound

movement of compression waves hitting our ears

Pitch

frequency of sound

Humans can hear

frequencies from 20Hz to 20,000Hz

Loudness

amplitude of sound

Loudness’ Measure

decibels

AM

amplitude modulation (around first)

FM

frequency modulation

AM’s Measure

kilohertz

FM’s Measure

megahertz

How a Radio Works

by transmitting and receiving electromagnetic waves

Natural Frequency

frequency of the vibration that an object vibrates at

Natural Frequency Depends On

tightness, length or weight of string

Resonance

occurs when a force exerted on an object exactly matches the natural frequency of the object

For Resonance

only a small force is needed for a big response

Standing Wave

appears to stay in one place

Fundamental

natural

Harmonics

fundamentals and multiples of its frequencies

Count by the

antinodes

f=

frequency in Hz

N=

number of the harmonic

X=

frequency of the fundamental (1st) harmonic

Nodes

points where the string doesn’t move

Antinodes

points of the greatest amplitude

There are Always More

nodes than antinodes

Light

a wave that we see

Speed of light

300,000,000m/s

Light can

carry heat, has color, can be bright or dim

Ways light can be bent

by a lens, or reflected in a mirror

What makes light?

the movement of electrons in atoms produce light

Light gains energy by

electrons moving from lower to higher levels

When moving from lower to higher

they release energy

Electromagnetic spectrum

whole range of light

Light we see

only a small amount of all light

Light we see

light we can see, in the middle

low end of ES

radio waves

high end of ES

gamma rays

Polarizer

partially transparent material that only lets one angle of light through

Two polarizers in the same direction

light not blocked

Two polarizers in different directions

light can be blocked

Electricity

the flow of charge, or electrons

Charged

when charge builds up on an object or material

Repel

like charges

Attract

unlike charges

Electric charge

depends on the number of protons and electrons

Conductors

allow charges to flow easily (loosely bound electrons)

Insulators

does not allow charges to flow easily (tightly bound)

Electric circuits

any closed path in which electrons can flow

Closed circuit

flow of electrons is possible

Open circuit

gap in the circuit, electrons can’t flow

Voltage

can cause the flow of charges

Voltage measure

Volts (V)

Current

the amount of electricity flowing in a circuit

Current measure

amperes (A)

Resistance

property of a material to slow down electricity

More resistance=

less current

Resistance measure

Ohms (Ω)

Ohm’s law

I=V/R

Series

a single pathway circuit for electron flow

Open circuit is because

a break anywhere in the path

Electrons will not flow

when there’s a break in a series circuit

Adding total resistance

decreases total current

Parallel

branched pathway is formed for the flow of electrons

Electrons have options in

a parallel circuit

Homes are wired in

parallel

Resistor in each branch

operates independently of the others

Hydrogen bonds

water molecules weakly connect to each other by matching positive end to the negative end of another molecule

Solutions

a homogeneous mixture of two or more substances

Alloys

metal solutions

Solvent

does the dissolving, is present in the greatest amount

Solute

gets dissolved, all remaining parts or components

Solute dissolved

when particles are easily spread out

Colloids

heterogeneous mixtures that look like solutions

Suspensions

heterogeneous mixtures that settle on standing, can filter, particles are largest

Water

water molecule forms v shape, polar because it has two poles

Cohesion

attraction between water molecules

Adhesion

attraction of water molecules to other substances

Tyndall Effect

helps tell the difference between colloids and solutions

Dissociation

process in which ionic compounds dissolve into positive and negative ions