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formula of WEIGHT mass x gravity (Newtons; Pounds)
formula of DENSITY mass/volume (kg/m^3)
formula of CELCIUS 5/9 x (F-32)
formula of FARENHEITS (9/5 x C) +32
what is an absolute zero? -273 C or 0 K
VELOCITY formula d/t (m/s; miles/hour)
ACCELERATION formula the change in velocity / time a=(Vf-Vo)/t (m/s^2) Vf = final velocity; Vo = original velocity
FORCE formula Newtons Second Law of Motion m x a (kg m/s^2 = Newton)
WORK formula F x d (kg m^2/s^2 = Joules)
POWER formula P=W/t (kg m^2/s^3 = Watts)
PE formula Potential Energy PE= m x g x h (Joules) m-mass; g-gravitational constant; h-height
KE formula Kinetic Energy KE= 1/2 (m x v^2) (Joules) m-mass; v-velocity
WAVE EQUATION formula C = wavelength (Angstrom) x frequency (Hz) c = 3 x 10^8 m/s
1 Angstrom = how many meters? 1 A = 10^-10 meters
the Law of Conservation of Energy E=mc m-mass; c-speed of light (constant: 3*10^8 m/s)
Plank's Particle Theory E= h x v e - energy of photon (eV); h (Planks constant)=4.15 x 10^-15 eVs v-frequency (Hz)
how many Joules is 1 eV? 1.6 x 10^-19 Joules 1eV=energy of 1 electron passing through the potential difference of 1 Volt
maximum number of electrons in each shell 2n^2 K=2; L=8; M=18; N=32
mass of proton and neutron 1.67 x 10^-27 (kg) 1 (amu)
mass of electron 9.1 x 10^-31 (kg) 1/1837 (amu)
definition of isotope An atom that has gained or lost neutrons from its natural state is called an isotope Hydrogen – 1 proton and 0 neutrons Deuterium – 1 proton and 1 neutron Tritium – 1 proton and 2 neutrons
Octet rule Atoms like to have 8 electrons in the outermost shell (except the K-shell)
“valence” of an atom The number of electrons in an atoms outermost shell determines its ability to bind with other atoms
Three fundamental units of physics: - length - mass - time
what is definition a MASS? Mass is the quantity of matter contained in an object Standard unit: kilogram or gram (Pound or dyne)
what is definition of WEIGHT? Weight is the force that gravity is pulling on a mass. Standard unit: Newton (pounds)
First Law of Newton A body in motion will remain in motion while a body at rest will remain at rest unless a force acts upon it.
Third Law of Newton For every action there is an equal and opposite reaction
Boiling point of water 100 C or 212 F
Area of a circle A=3.14 x r^2
Circumference of a circle c=2 x 3.14 x r
Electrostatics Electrostatics is the branch of physics that deals with stationary electrical charges
What give an object an electric charge? A differing number of electrons and protons will give an object an electrical charge
unit of electrical charge? coulomb (C)
Laws of Electrostatics 1. Repulsion / Attraction 2. Inverse Square Law 3. Coulomb’s Law 4. Distribution 5. Concentration 6. Movement
Coulomb’s Law F = (k q1 q2)/ r2 F = electrostatic force in Newtons k = 9 x 109 N m 2/C2 q = charges in coulombs r = distance between the objects in meters
Inverse Square Law - the force of attraction or repulsion between two objects is inversely proportional to the square of the distance between them
Distribution - electrical charges reside on the external surface of conductors and are equally distributed throughout non-conductors
Repulsion / Attraction - like charges repel, unlike charges attract
Concentration - the greatest concentration of charges is on the surface where the curvature is sharpest
Movement - only negative charges (electrons) move along a conductor
3 methods of electrification of an object 1) friction 2) contact 3) induction
Friction - the removal of electrons from one object by rubbing it with a different object - both objects are neutral - the simplest and most fundamental method of electrification - most likely during cold and low humidity conditions
Contact - when a charged object touches an uncharged object, the second object acquires the same charge as the first - a negatively charged object (excess of electrons) will give electrons to a neutral object – it gains a negative charge
Induction - strongly charged object (A) will influence charges of weakly charged/uncharged object (B) w/o phys. contact - charges will be induced to move withinB; when object A is removed, object B will return to its norm. state -can only occur within a conductor
“electric field” Surrounding every charged body is a region in which a force is exerted on another charged body
Definition of conductivity The ability of a material to allow the free flow of electrons
Conductors have a relatively free flow of electrons (little heat is lost) Ex: copper, gold, silver, aluminium
Non-conductors or insulators do not allow electrons to move freely Ex: plastic, rubber, glass
Semiconductors can be either conductors or insulators Ex: silicon, germanium
Superconductors have no resistance to the flow of electrons Ex: ceramics, titanium
Three conditions that will allow a current to flow: 1) in a vacuum 2) in a gas 3) in a metallic conductor
A circuit is the path over which the current flows
A source of electrons 1) battery (DC) 2) generator (AC)
Three factors characterize a simple circuit: 1) potential difference 2) current 3) resistance
Potential difference also termed emf (electromotive force) the difference in electrical potential energy between two points in a circuit
Volt is a unit for potential difference (V) - 1 volt is 1 joule of work done on 1 coulomb of charge - is the potential difference that will maintain a current of 1 ampere in a circuit whose resistance is 1 Ohm
Current - the amount of electrical charges flowing per second - electrons / second - unit: ampere (A) or milliampere (mA)
1 ampere 1 ampere is 1 coulomb of charge flowing per second - 1 amp = 1 coulomb/second - 1 coulomb = 6.3 x 1018 electrons  1 amp = 6.3 x 1018 e- / second
Resistance - anything that opposes or hinders the flow of electrical current - unit: Ohm - resistance is inherent (within the conductor) and added (load)
Inherent resistance (iR) in a wire is dependent upon: 1)material (conductor–low R; insulator–high R; semiconductor–intermediate;superconductor–no R) 2) length of wire (the longer the wire,more R) 3) cross-sectional area ( the greater the area, less R) 4) temperature ( the greater the T, greater R)
RESISTANCE formula R = p (L/A) R = resistance p (rho) = resistivity coefficient L = length A = cross-sectional area
POWER RULE formula P = IV (Watt) 1 watt is one ampere of current flowing through one volt per second
LOSS OF POWER formula P = I2R I - current in amp
Simple Electric Circuit components 1) Source (battery) 2) Conductor 3) Resistance or load 4) Switch 5) Voltmeter 6) Ammeter 7) Capacitor
Ohm’s Law The mathematical relationship between current, potential difference, and resistance in a circuit: I = V/ R I = electrical current in amperes (A) V = potential difference in volts (V) R = resistance in ohms ()
What does voltmeter measure? The voltmeter measures potential difference and is placed in parallel either around the resistance or the source
What does the ammeter measure? The ammeter measures current and is placed in series anywhere on the circuit
What does a capacitor do? It stores electrical energy
What is a generator? what are the 2 main parts of generator? A generator is a device that converts mechanical energy to electrical energy by means of electromagnetic induction Two major parts of a generator: 1) the field magnet 2) the armature (conductor)
What does the armature do? The armature moves (mechanical energy) through the magnetic field that induces current in the armature
sources of mechanical energy: - steam turbine - water (hydroelectric power) - nuclear energy - gas/coal/oil - wind - solar
How does Simple generator work? the field magnet provides magn. field; armature moves through the mag.c field; armature attached to slip rings;carbon brushes allow the slip rings to stay in contact with the wire to the load. AC is generated. 1 cycle is one full rotation of the armature
Resistance in an alternating current circuit: 1) inherent resistance (same as in wire) 2) inductive reactance (R caused by the magnetic field expanding and contracting over its own conductor) 3) capacitive reactance (R caused by the change in polarity of a capacitor in the circuit)
“Impedance” (Z) The total apparent resistance in an AC circuit (a combination of the three)
Ohm’s Law for AC I = V/ Z
A direct current (DC) generator uses “commutator rings” instead of slip rings It produces pulsating direct current
A motor converts electrical energy to mechanical energy Passing a current through a conductor that is inside a magnetic field will create motion in the conductor
To determine the direction of the motion induced in the conductor, use Fleming’s Left Hand Motor Rule
Two basic types of motors: 1) direct current motors (basically the opposite of a direct current generator) 2) alternating current motors a) synchronous motors b) induction motors
Synchronous AC motors - the motor turns at the same speed as the incoming current (60 cycles per second) - they are used in clocks and some x-ray exposure timers
Induction AC motors: - two basic parts: 1) stator ( bars of copper around an iron core) 2) rotor (pairs of electromagnets arranged around the rotor)
Ferrous materials: 1) iron 2) nickel 3) cobalt
Classifications of magnets 1) natural: lodestone (iron oxide or magnetite - Earth) 2) artifical permanent: alnico, steel 3) electromagnet - a magnet created by placing a piece of iron in a coil of current-carrying wire. it is only a magnet when the current is flowing.
3 Laws of Magnetism: 1) every magnet has two poles: north and south 2) like poles repel and unlike poles attract 3) the force of attraction or repulsion follows the Inverse Square Law
magnetic domains (dipoles) Groups of atoms with their magnetic fields in the same direction 1 domain ~10^15 atoms A ferrous material has lots of domains, but they are in different directions Non-ferrous materials do not have domains, so they are unaffected by a magnet
How is a magnetic field created? when a charged particle (an electron) is in motion or spinning, mag field is created
What is a magnetic field? The area of influence surrounding a magnet is called the magnetic field. The field is made up of lines of force (LOF) or flux lines. The stronger the magnet, the closed together the flux lines are
What is a field strength of a magnet? Field Strength is the number of flux lines (or lines of force) Measured in Webers (Wb) 1 Wb = 10^8 flux lines
Flux density? Flux Density is the number of flux lines per square meter Flux Density = field strength/area Measured in Tesla (T) or Gauss (G) 1 Tesla = 1 Wb/m2 1 Tesla = 10,000 Gauss
Flux density of earth? MRI? The Earth = .5 G or .00005 T A household magnet = .1 T MRI = .5 to 3 T
Characteristics of flux lines: 1) outside magnet,flux lines go from N to S 2) inside magnet, from S to N 3) fl repel when they go in same direction; attract when they go in opposite directions 4) the mag. field is distorted by a ferrous object, but unaffected by a non-ferrous object
Magnetic induction if a ferrous object is placed into a magnetic field, it temporarily becomes a magnet - some materials have the ability to retain their magnetic characteristics (they can become artificial permanent magnets)
Magnetic permeability is the ease that a material becomes magnetized or de-magnetized
Magnetic retentivity is the ability of a material to retain its magnetism
Classifications of the Magnetic Properties of Matter 1. Ferromag. ( high mag. perm.; attracted by mag.): iron, nickel, cobalt 2. Paramag. (low perm.; weakly attracted.):platinum, Al, gadolinium 3. Non-mag. (no perm.;not affected): glass, plastic, wood. 4. Diamag. (weakly repelled): beryllium, bismuth, lead
Created by: sunkissfl