2013 AC Science Cheat Sheet · 2013 AC Science Cheat Sheet. Step 3: Research, Write detailed and...
Transcript of 2013 AC Science Cheat Sheet · 2013 AC Science Cheat Sheet. Step 3: Research, Write detailed and...
SI Units (Metric)
Quantity Name Symbol of Unit
meter m length centimeter cm
kilometer km
kilogram kg mass gram g
milligram mg
second s time minute min
hour hr
force Newtons N
temperature Kelvin °K
Metric Conversion
King Henry Died By Drinking
Chocolate Milk!
Conversion Factors
Factor US Unit Multiply by:
Equals METRIC unit
Length Inches 2.54 Centimeters (cm)
Feet .3048 Meters (m)
Miles 1.61 Kilometers (km)
Weight Ounces 28.35 Grams (g)
Pounds .45 Kilograms (kg)
Volume Fluid Ounces
29.57 Milliliters (mL)
Gallons 3.79 Liters (L)
Temperature Fahrenheit (0F-32) X 5/9
Celsius (0C)
Factor Metric Unit Multiply by:
Equals US unit
Length Meters 3.28 Feet
Kilometers .62 Miles
Weight Grams .035 ounces
Volume Liters 4.23 cups
Liters .26 gallons
Temperature Celsius (0CX1.8)+ 32
Fahrenheit
Factor Equation Equals Metric Unit
Temperature 0C+273 Kelvin (K)
K-273 Celsius (0C)
Scientific Method/ Experimental Design/
PHEOC
Step 1: Ask a question or have a purpose for
investigation.
Step 2: Develop a Hypothesis (3rd
person). Try NOT to
use an If…Then statement. Additionally, your
hypothesis needs to be TESTABLE!
Quantity Name Symbol
of Unit
meters 2 m 2
area centimeters 2 cm 2
millimeters 2 mm 2
meters 3 m 3
volume centimeters 3 cm3
millimeters 3 mm 3
- kg/m3
density - kg/cm3
- g/cm3
2013 AC Science Cheat Sheet
Step 3: Research, Write detailed and PRECISE
procedures, identify your variables and control(s), and
conduct your experiment. Don’t forget that valuable
experiments usually consist of multiple trials. Remember
the following terms:
o Independent Variable: (AKA
Manipulated Variable): this is what you
change in an experiment…what you
manipulate.
o Dependent Variable: these are your
observations based upon what you
changed in your experiment. Your
dependent variable DEPENDS on your
independent variable(s).
o Control: your point of reference in an
experiment. This would be something
that is not manipulated.
o Accurate: exactness of a measurement
o Precision: repeatable with the SAME
results
o Reliable: trustworthy research
o Valid: based on facts
Step 4: Record ALL Data (Quantitative (number data)
and Qualitative (quality/characteristic data)) and
Observations.
Step 5: Analyze your data and construct a well-
developed Conclusion (in 3rd
person).
Theory: a testable idea for an unexplained phenomenon.
Law: states a fact, but does not explain why.
Tools
Mass = triple-beam balance or digital scale
Weight/Mass = Spring Scale or digital scale
Temperature = thermometer
Volume of regular solid = metric ruler/meter stick
Volume of irregular solid or liquids = beaker and
graduated cylinder
Heating liquids = Erlenmeyer flask and tongs.
Formulas in Physical Science
Speed = distance (D)/time(T)
o Measured in meters/hour (base unit)
(m/hr) or (m/s)
Average Speed = total distance/total time
o Measured in meters/second (base unit)
(m/s)
Acceleration = force (F)/mass (m)
o Unit = meters/second (m/s)
Force = mass (m) X acceleration (a)
o Unit = newton (N)
Mass = force (F) X acceleration (a)
o Unit = grams (g)
Average Acceleration = final velocity-starting
velocity ÷ time it takes to change velocity
o Unit = meters/second2 (m/s
2)
Net Force…
o Traveling in the same direction = ADD
o Traveling in opposite direction = subtract
o Unit = newtons(N)
Work = Force(F) X Distance(D)
o Unit = Newton/Meter AKA a JOULE (J)
Power = Work(J) ÷ Time(T)
o Unit = Watt (W)
Pressure = Force (F) ÷ Area(A)
o Unit = Pascal (Pa)
Density = Mass(m)÷ Volume(V) o Unit = g/cm
3
Concentration = mass of solute ÷ volume of
solvent
o Unit = g/mL
Velocity of a Falling Object = Δv(change in
velocity) = gravity constant (g = 9.8m/s2) X
Time(T)
o Δv = g X t
o Unit = m/s
Rearrange to find time…
o T = Δv ÷ g
o Unit = seconds (s)
Volume of a REGULAR object = V (volume) =
length X width X height o Unit = cm
3
Volume of an IRREGULAR object…use
DISPLACEMENT METHOD (graduated cylinder
with water). The change or displacement of
water is your volume.
o Unit = mL (1mL = 1cm3)
How many Electrons will fit in each energy
level?
o 2(N2) N=the energy level number
Momentum…
o P(Momentum) = Mass(m) X Volume(v)
o Unit = kg*m/s (include a
direction…N,S,E,W)
Mechanical Advantage (MA)= output force ÷
input force
o Unit = Newton (N)
Mechanical Efficiency = work output ÷ work input
X 100
o Unit = percentage
Kinetic Energy(KE) = mass(m) X volume2 (v
2) ÷
2
o Unit = Joules (J)
Gravitational Potential Energy (GPE) = weight
(N) X height (m)
o Unit = Joule (J)
Mechanical Energy (ME) = Potential energy (PE)
+ Kinetic energy (KE)
o Unit = Joule(J)
Ohm’s Law
Resistance (R) = Voltage (V) ÷ current (I)
o Unit = Ohm (Ω)
OR
Voltage (V) = Current(I) X Resistance (R)
o Unit = Volts (V)
Electric Power = Voltage (V) X Current (I)
o Unit = Watt (W)
Electrical Energy = Power (P) X Time(T)
o Unit = Kilowatt hours (kWh)
Wave Speed (v) = Wavelength (λ – Greek letter
lambda) X Frequency (f)
o Frequency’s unit is Hertz(Hz)
o Unit for Wave speed = m/s
Can Rearrange the formula…
Wavelength (λ) = wave speed (v) ÷ Frequency
(f)
Frequency (f) = wave speed (v) ÷ Wavelength
(λ)
Mass vs. Weight
Mass is the amount of matter in an object, measured in
grams by using a triple-beam balance or digital scale.
Mass is CONSTANT and does NOT change based on
your location in the universe.
Weight is a factor of gravitational force measured in
Newtons by using a digital scale or spring scale. Weight
FLUCTUATES based on your location in the universe.
Laws in Physical Science
Law of Conservation of Mass/Matter: states matter
cannot be created or destroyed during a chemical or
physical change
Law of Conservation of Energy: states energy cannot be
created or destroyed
Universal Law of Gravitation: states all objects are
attracted to each other due to gravity.
o Part 1: The larger the mass, the greater
the gravitational pull and vice versa.
o Part 2: The greater the distance, the
lesser the gravitational pull and vice
versa.
Newton’s First Law of Motion: states an object in motion
stays in motion until acted upon by an unbalanced force.
Example: bumper cars and FRICTION!
Newton’s 2nd
Law of Motion: (sometimes called the Law
of Inertia) states the acceleration of an object depends
on the mass of the object and the force applied.
Example: compare pushing an empty grocery cart to a
FULL grocery cart.
Can be expressed as an equation: F=m
X a or a= F ÷ m
Newton’s 3rd
Law of Motion: states for every action,
there is an equal and opposite reaction. Example:
kicking off a wall in a swimming pool.
Law of Reflection: states that the angel of incidence is
equal to the angle of reflection. Light reflects off a
surface at the same angle that light strikes the surface.
Charles’ Law: states that for a fixed amount of gas at a
constant PRESSURE, the volume of the gas increases
as the temperature increases and vice versa. Example:
Mylar balloons shrinking in cold weather and swelling in
hot weather.
Boyle’s Law: states that for a fixed amount of gas at a
constant TEMPERATURE, the volume of a gas
increases as the pressure increases (inversely
proportionate) and vice versa. Example: Blowing
bubbles at the bottom of the pool…the bubbles increase
in size as they rise to the top of the water.
Law of Momentum: states that any time 2 objects collide,
the total amount of momentum remains the same.
Chemistry Cheats
Examples of Chemical Properties
Examples of Physical Properties
Reactivity with Oxygen Thermal Conductivity
Flammability State
Reactivity Density
Solubility
Ductility
Malleability
Examples of Chemical Changes
Examples of Physical Changes
Soured Milk Change in state
Effervescent tablets Slicing
Rusting Tearing
Tarnishing Mashing
Forming of a gas Dissolving
*Changes the Composition*
*NO change in composition*
*Not easily reversed* *May be reversed*
The 5 States of Matter
Solids have particles that are tightly packed and
VIBRATE in place.
Liquids have particles that are just far enough to SLIP
PAST each other.
Gases are particles that are WIDELY SPREAD.
Plasmas are gas particles that carry an ionic (electric +
or -) charge. Only occurs on Earth as lightning.
Bose-Einstein Condensate (BEC) occurs as an atom
(like rubidium) condenses hence its name. BEC’s were
discovered in 1995, but predicted in the 1920’s by Bose
and Einstein. Think of the BEC like an atomic “blob.” As
an atom approaches Absolute Zero (the point where all
matter stops moving), the particles in the atom clump up
and form a “blob-like” substance.
Changes in State
Changes in state are simply caused by the adding and
removing of energy. See the table below.
Adding Energy = Endothermic
Removing Energy = Exothermic
Periodic Table
Vertical columns on the Periodic Table are called
GROUPS or FAMILIES and share common
characteristics.
Horizontal rows on the Periodic Table are called
PERIODS. Elements chance “periodically” as you move
from left to right across the table. The pattern occurs
every 7 elements.
The Lanthanides and Actinides (so called because they
begin with the elements Lanthanum and Actinium) are
the 2 bottom rows that are pulled out separate at the
bottom of the table. This is simply to make the table
more user friendly. They are not “special.”
Atomic Theory
Date Scientist Credits Democritus 440 BCE Naming the atom, a
particle that cannot be cut
Aristotle 322 BCE Particles could be infinitely (he was wrong)
Dalton 1803 Developed Atomic Theory: all substances made of atoms, cannot be created/divided/destroyed, join to make new substances. (Almost right!)
Thomson 1897 Plum Pudding Theory…Electrons were the “plums”; Cathode Ray Tube
Rutherford 1909 “shooting gallery”; named the nucleus and claimed it was positively charged (protons)
Bohr 1913 Atomic structure – electrons orbit positively charged nucleus.
Shrodinger and Heisenberg
Later 20th
Century
Modern Atomic Theory…electrons spin randomly around the positively charged nucleus in electron clouds.
Three Kinds of Elements on the Periodic Table
Metals are found on the left of the zigzag line on the
table. Metals are solid at room temperature, typically
shiny, malleable, ductile, and good conductors.
Nonmetals are found to the right of the zigzag line on the
table. Nonmetals are typically gases at room
temperature. They are not shiny, malleable, or ductile.
Nonmetals are not good conductors.
Metalloids are also called semiconductors. They are
found along the zigzag line on the table. Metalloids have
properties of both metals and nonmetals. Metalloids are
responsible for many of our technological devices we
use.
Sample Element from the Periodic Table
There are 3 types of particles found in an atom:
Protons are POSITIVE and located in the nucleus.
Protons are medium-sized in relation to mass.
Neutrons are NEUTRAL are located in the nucleus
tightly packed with the Protons. Neutrons are the
HEAVIEST particles and are responsible for the MOST
of the mass of an atom.
Electrons are NEGATIVE are found in the ENERGY
LEVELS/ ELECTRON CLOUDS/ ORBITS that circle the
nucleus. Electrons are insignificant in mass (VERY
small).
Atomic Structure
Symbol
Name of
Element
Atomic Number
Atomic
Mass
Valence
Electrons
Energy Level #1
Energy Level #2
The Number of Protons and Electrons = the Atomic
Number (in a NEUTRAL atom…NOT an ion!)
The Number of Neutrons can be found by taking the
difference between the Atomic Mass (rounded to the
nearest whole number) and the Atomic Number.
Atomic Mass can be found by adding Protons and
Neutrons. Atomic Mass is measured in Atomic Mass
Units (AMU’s) and is an average of naturally occurring
elements, hence the decimals.
Valence Electrons are the “hook up” electrons and
define an elements ability to bond with other elements to
form molecules and compounds. The “magic numbers”
for Valence Electrons and bonding are 2 (for the lowest
numbers on the table) and 8 for the rest of the table.
Building with Atoms
An ATOM is the smallest unit of an element that can still
be identified to have qualities of the element.
An ELEMENT is a substance that CANNOT be broken
down into a more simplistic substance by ANY chemical
means.
A MOLECULE is a chemical combination of any 2 or
more ATOMS. Example: O2 OR H2O
A COMPOUND is a chemical combination of any 2 or
more ELEMENTS (has a symbol on the Periodic Table).
Example: H2O
**ALL compounds are molecules, but NOT all molecules
are compounds. Example: O2**
IONS are POSITIVELY or NEGATIVELY charged
elements.
ISOTOPES are different versions of the same element
that have varying atomic masses and number of
neutrons.
Mixture – combination of substances that are NOT
chemically combined – Example: a tossed salad
Suspension – mixture where the particles settle out –
Example: Italian salad dressing
Solution – mixture where a solute is dissolved into a
solvent, but can be separated. Example: salt water
Solute – the particle that is dissolved in a solvent.
Example: salt
Solvent – the particles into which a solute is dissolved.
Example: The UNIVERSAL SOLVENT – WATER!
Colloid – mixture where solid particles separate.
Example: Jello or Milk
Chemical Equations
Prefixes for Writing Chemical Equations
Number of Atoms Prefix
1 Mono
2 Di
3 Tri
4 Tetra
5 Penta
6 Hexa
7 Hepta
8 Octa
9 Nona
10 Deca
Bonding: 3 types
Ionic – the gaining or losing of ELECTRONS. Results is
a positive or negatively charged atom. If electrons are
LOST, the atom is POSITIVE. If electrons are GAINED,
the atom is negative. Normally occurs between a metal
and a nonmetal.
Covalent – the sharing of electrons. Usually a nonmetal
and another nonmetal.
Metallic – bonding between 2 or more metals. Can be
ionic or covalent.
Counting Atoms
H2O – has 3 atoms (2 H and 1 O)
2H2O – has 6 atoms (4 H and 2 O) – you simply
distribute the Coefficient throughout the compound.
YIELDS
SUBSCRIPTS…NO
TOUCHY!!
Balancing Equations
Here is a website for you to practice with!
http://richardbowles.tripod.com/chemistry/balance.htm#p
art1
Types of Chemical Reactions
Acids and Bases
ACIDS are compounds that increase the number of
hydronium (positive) ions when dissolved in water. Acids
tend to be sour and corrosive. Acids turn litmus paper
RED!
BASES are any compounds that increase the number of
hydroxide (negative) ions when dissolved in water.
Bases are typically bitter and slippery. Bases turn litmus
paper BLUE!
pH Scale
Physics Cheats
Speed Graph
VELOCITY is SPEED with a DIRECTION!
ACCELERATION is ANY change in VELOCITY, so ANY
change in SPEED OR DIRECTION. Acceleration can be
positive or negative (deceleration). The faster the
velocity changes, the greater the acceleration.
Continuous Acceleration is achievable by circular motion
or Centripetal Acceleration. The object is CONSTANTLY
changing direction while traveling in a circle.
Acceleration Graph
Force
A FORCE is any push or pull.
Forces can be calculated. NET FORCE is the total of
ALL forces acting on an object, measured in Newtons.
Forces acting in the SAME direction are ADDED
together.
Take the DIFFERENCT between forces acting in
OPPOSITE directions.
BALANCED FORCES occur when net force equals
ZERO. This occurs when an object is NOT moving OR
moving at a CONSTANT VELOCITY (no speed or
direction changes).
UNBALANCED FORCES occur when an object is in
motion. Unbalanced forces CAUSE changes in motion.
FRICTION is a force that opposes motion. Friction is
EVERYWHERE! There are 2 kinds: Kinetic (friction in
motion) and Static (object is not moving).
GRAVITY is a force of attraction between objects due to
their masses. ALL objects are subject to gravity! Gravity
is a result of mass! We must overcome gravity to move!
Synthesis
Decomposition
Single
Displacement
Double
Displacement
ALL objects accelerate towards the Earth at the SAME
rate. That rate is 9.8m/s2. The variances we see in
objects falling at different rates is caused by FRICTION!!
Air Resistance = FRICTION!!
TERMINAL VELOCITY is the point at which a falling
object ceases to accelerate and falls at a CONSTANT
rate.
FREE FALL is ONLY possible when an object is
weightless, therefore FREE FALL is ONLY possible in
space or when an object is in ORBIT. Orbiting has 2
motions…forward and down (free fall).
Projectile motion is a combination of 2
motions…horizontal THEN vertical (forward THEN
down). This allows us to see the curved path that an
object creates as it is thrown.
INERTIA is the tendency of an object to resist a change
in motion. INERTIA holds you in your seat on an inverted
roller coaster. The GREATER the MASS, the GREATER
the INERTIA!
Work
WORK is done when a force causes an object to move
in the SAME direction as the force.
Kinetic Energy = energy in motion
Potential Energy = energy of position
POWER is the rate at which WORK is transferred.
Simple Machines
MACHINES make work easier by changing the SIZE or
DIRECTION of a force.
WORK INPUT = work done on a machine (what you put
in)
WORK OUTPUT = work done BY the machine
PERFECT Machines (100% Efficiency) are NOT
possible due to the existence of FRICTION!!
Levers
LOAD = what you are moving
FULCRUM = fixed point where a pivot occurs
Pulleys
Fixed Pulley (Elevator) Movable Pulley (Distance)
Block and Tackle Pulley (share the load)
First
Class
Second
Class
Third
Class
Wheel and Axle
Wheel is larger than the axle, so
the output is greater than the input.
Inclined Plane
Increase distance, but decrease
input force.
Wedge
Pair of inclined planes that move.
Output force is greater than the input.
Distance is increased.
Screw
Small force applied over a long
distance and vice versa. A type of
inclined plane.
COMPOUND MACHINES are any combination of SIMPLE
MACHINES!
Heat Transfer: 3 types
Temperature: measure of the average kinetic energy of the
particles in an object (technically there is NOT hot or cold!)
Radiation: transfer in waves – heat you can feel
Conduction: transfer by direct contact – touching a hot pot
Convection: heat transfer through a fluid (liquid or gas) in a
circular pattern – like water boiling in a pot
Temperature Scale Comparison
Fission and Fusion
FUSION: Nuclei join together to form a larger nuclei.
This is what happens with our Sun!
FISSION: Large nuclei splits and forms 2 new nuclei.
HALF-LIFE: the time it takes for HALF of a given sample to
decay so it is no longer detectable.
Energy Conversion
Energy Conversion: changing of energy from one form to
another. Energy is never created or destroyed, but can be
transferred. Thermal Energy (heat) is ALWAYS part of an
energy conversion.
Conductors and Insulators
Conductors Insulators Curling iron Flannel shirt
Cookie sheet Oven sheet
Iron skillet Plastic spatula
Copper pipe Fiberglass insulation
Stove coil Ceramic bowl
Waves, Light, and Sound
Waves – any disturbance that transmits itself through matter
or empty space
Medium – substance through which a cave can travel (solid,
liquid, or gas)
2 kinds of waves:
Transverse: looks like a rope being moved;
contains crests (the high point of the wave) and
troughs (the lowest point of the wave). Water
waves are transverse waves.
Longitudinal: looks like a slinky or spring;
contains compressions (areas where the coils are
tightly pressed together) and rarefactions (areas
where the coils are spread apart). Sound is a
longitudinal wave.
Surface Waves – combination of both types, like an ocean
wave
Wavelength – distance from crest to crest or trough to
trough, measured the same in both types of waves.
Wavelength can be calculated by
multiplying wave speed times frequency; measured
in meters
More energy = shorter wavelength
Less energy = longer wavelength
Amplitude – height of a wave from a rest position - can be
measured from rest position to the top of the crest or rest
position to bottom of trough
Frequency – number of waves produced in a given amount of
time
Calculated by dividing wave speed by
wavelength, measured in Hertz (Hz)
Higher frequency = more energy
Lower frequency = less energy
High and Low Frequency
Wave Speed –
speed at which a
wave travels
Calculated by multiplying wavelength times
frequency, measured in meters per second
Frequency and Wavelength – as frequency increases,
wavelength decreases – they are inversely proportionate
Reflection – wave bounces back after hitting a barrier – echo
is a sound wave reflecting
Transmitted – when waves pass through a substance
Refraction – bending of a wave as the wave goes from one
medium to another at an angle – this is how we see a
rainbow using a prism or after a rain shower. This is caused
by the wave changing speed as it changes medium.
Diffraction – bending of waves around a barriers or through
an opening – this why you can hear music before you can see
it
Waves are energy, therefore they can be in the same place
at the same time (unlike physical objects)…waves can meet,
travel thru each other, and keep going (overlapping)
Interference - When waves overlap
Constructive interference – crests or troughs
overlap…energy is combined…new wave has higher crests
and deeper troughs – larger amplitude.
Destructive interference – crest from one & trough
from another overlap…smaller amplitude – possibly destroy
wave.
Standing Wave – caused by loops of interference…looks like
wave is not moving – formed from transverse waves (like a
guitar string) and longitudinal waves.
Frequency at which standing waves are made are called
resonant frequencies.
Resonance – object vibrates and causes another object to
vibrate (mirror with bass sound, drums, singing in shower,
xylophone, etc.)
Sound waves are longitudinal and MUST have a medium to
travel. Sound travels by creating vibrations. Therefore, the
more tightly packed the particles are – the faster the sound
wave can travel. So, sound travels fastest in solids, followed
by liquids, and lastly the slowest in gases. Temperature also
affects the speed of sound. The cooler the medium, the
slower the sound.
The ear – sound enters through the outer ear, is amplified by
the middle ear (with the bones: hammer, anvil and stirrup),
and lastly changed into electrical signals to be sent to the
brain in the inner ear.
Speed of sound – Chuck Yeager was the first person to fly a
jet faster than the speed of sound. When an object
approaches the speed of sound, gases begin behaving more
like a fluid. When the objects reaches the speed of sound and
then begins to move faster it is called breaking the sound
barrier. This act results in what is called a sonic boom. The air
particles are moving and colliding so quickly that it generates a very
loud sound.
Speed Variances Based on State
Sounds travel fastest through solids, then liquid, and gases
are the slowest!
Pitch – How low or high a sound seems – pitch is related to
frequency, the higher the pitch – the higher the frequency.
Doppler Effect – apparent change in frequency of a sound
caused by the motion of the listener or the source of the
sound. Like hearing an ambulance, fire truck, or police car’s
siren.
Loudness – measure of how well a sound can be heard – air
particles are moving faster in a loud sound. Loudness is
measured in decibels (dB) Average humans can hear a low as
0 dB. Sounds higher than 120 dB are painful.
Amplitude – the height of a wave from the rest period. When
you apply for force to increase loudness, you increase the
height of the wave. Therefore loudness and amplitude are
related.
You can see the relationship between frequency and
amplitude by using an oscilloscope. It takes longitudinal
sound waves and creates a transverse wave, so you can “see
the sound.”
Electromagnetic Spectrum
Electromagnetic spectrum (EM Spectrum): diagram of ALL
frequencies based on WAVELENGTH of electromagnetic
radiation!
Radio waves have LONGEST wavelength and LOWEST
frequency…Gamma Waves have the SHORTEST wavelength
and HIGHEST frequency!
Electromagnetism
Law of Electric Charges – like charges repel and opposite
charges attract
Electric Force – force between 2 charged objects
Electric Field – region surrounding a charged object where an
electric force continues to exert on another object
Friction – electrons are wiped from one surface to another
(rubbing a balloon on your head)
Conduction – electrons are transferred by direct contact
(when you are shocked)
Induction – uncharged object is affected without direct
contact (your hair sticking out after you brush it)
Electroscope – allows you to detect charges
Conductors – charges flow easily
Insulators – charges do not flow easily
Static electricity – electric charge at rest on an object
Electric discharge – charges move off of an object (shocking
yourself on a doorknob or lightning)
Electric Current – rate at which charges pass a given point
A/C – Alternating Current: charges flow in both directions
(anything that plugs in)
D/C – Direct Current: charges only flow in one direction
(anything that takes a battery)
Electric Field
Electric Force
Voltage – potential difference between 2 points on a circuit;
measured in Volts (V)
Resistance – “electrical friction” the opposition to flow of a
charge; measured in Ohms (Ω)
Ohm’s Law – states that there is a direct correlation between
resistance and voltage for individual elements. Poor
conductors have a high resistance; Good conductors have low
resistance
Formula: Resistance(R) = Voltage (V) divided by
Current (I)
Expressed in Ohms (Ω)
You can rewrite the formula to find Voltage by
multiplying Current times Resistance
Best wires: short, fat, and cool
Resistance increases based on thickness of wires, length of
wires, and temperature of the material.
Cells – changes chemical or radiant energy into electrical
energy
Electrolyte: mixture of chemicals that allows charges
to flow
Wet Cell: have liquid electrolytes (a liquid can
complete the circuit)
Dry Cell: have solid electrolytes
Thermocouple: converts thermal energy to electrical energy
Photocells: converts light energy to electrical energy (solar
calculator)
Electric Power: rate at which electrical energy is converted to
other types of energy
Circuit: a closed path that forms a loop
Switch: can be used for safety reasons to control a circuit
A circuit MUST be CLOSED in order for the charge to flow!
Series Circuit – all parts are connected in s single loop – when
one light goes out – they all go out. Only one way in and one
way out (old Christmas tree lights)…bulbs burn equally bright,
but get dimmer as you add more – this is because the charge
has further to flow – you are increasing the resistance
Parallel Circuits – all parts are connected side-by-side – when
one light goes out – the charge can bypass and move to the
next light. All bulbs receive the maximum amount of charge;
therefore they always burn their brightest. This is why you
can plug in your hair dryer, radio, and phone charger in at the
same time!
Circuit Safety – all buildings/constructions are made with an
“electrical hub” or a fuse box/circuit box/breaker box. These
boxes control the charges flowing through the building. Inside
the boxes are switches controlled by FUSES. Fuses expand
and contract as charges flow through the box. If the fuse
detects too much charge flowing it will expand and close the
switch connected to that part of the building – therefore
shutting off all power to the area for safety reasons. You may
have experienced this is your home by having too many
things plugged in.
Magnets
Magnets – any material that attracts iron or things made
from iron
All magnets have 2 poles – north and south
Like poles repel, while opposite poles attract
Magnetic Force – spinning electric
charges in a magnet generate this
force
Magnetic Field – region that
surrounds a magnet where the
forces act
Ferromagnetic Material – objects made from iron, nickel, or
cobalt
Domains – areas inside the magnet that hold groups of
atoms.
When domains line up – the magnet is magnetized. When the
domains are knocked out of alignment or disrupted – the
magnet is no longer magnetized (demagnetized).
Creating Magnets – you can create a magnet by rubbing a
ferromagnetic material on a magnet. This creates relatively
weak and temporary magnets only.
Cutting a magnet – when you cut or break a magnet you end
up with 2 new magnets. Whatever end breaks off (North or
South) will regenerate after the domains realign and you will
now have 2 magnets instead of 1.
Destroying magnets – magnets can be destroyed by heating,
hitting the magnet with a dense object, or striking an object
with the magnet. Anything that causes the domains to be
knocked out of alignment will destroy a magnet.
Don’t forget the Earth is like a giant bar magnet. This is
proven by using magnetic compasses that point to magnetic
north.
Electromagnetism – an interaction between electricity and
magnetism
Electromagnet Diagram
AN ELECTRIC CURRENT CAN GENERATE A MAGNETIC FIELD!!
Creating electromagnets – you can take a piece of
ferromagnetic material and wrap a piece of copper wire
around it creating a coil. This coil is called a SOLENOID. If you
attach the wires on each end to an electrical device (like a
battery); you have created an electromagnetic! If you want
to increase or decrease the power of the electromagnetic,
simply increase or decrease the number of coils of the
solenoid or you may choose to use a stronger ferromagnetic
material.
Electric Motors – changes electrical to mechanical; contains
an armature (loop or coil that can rotate). If the motor uses a
direct current, it may also have a commutator which reduces
the current
Galvanometer – device that measures current
Solenoid
Hans Christian Oersted discovered that electric currents can
produce magnetic fields.
Michael Faraday – tried to prove that an electromagnet could
induce (create) and electric current – he failed. However, he
did find that an electric current could be created by the
process of electromagnetic induction (creating a current by
changing a magnetic field).
Electric generator – uses electromagnetic induction to change
mechanical energy into electrical energy
Transformers – device that increases or decreases the voltage
of an alternation current