matter is made up of small particles called atoms. atoms are made up of smaller, sub-atomic...
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Matter is made up of small particles called atoms. Atoms are made up of smaller, sub-atomic particles called protons, neutrons, and electrons.
Sub-atomic particles have a basic property called electric charge.protons - positive chargeneutrons - neutral, no chargeelectrons - negative charge
Electric Charge and Static Electricity
Protons and Electrons determine chargeAtoms have equal numbers of protons (positive)
and electrons (negative) therefore, atoms are neutral, with no charge.
An atom that loses electrons will have more protons than electrons = positive charge.
An atom that gains electrons will have more electrons than protons = negative charge.
Electric Charge and Static Electricity
Electric Charge and Static ElectricityStatic electricity - the build up of electric charge due to the electrons transferring from one object to another. Electrons do not flow. Remain at rest = “static”.
Methods of Charging an ObjectI. Friction - when an object is rubbed, it will gain or lose electrons and will gain a positive or negative chargeglass rod rubbed with silk =glass rod loses electronsplastic rod rubbed with fur = plastic rod gains electrons
Balloon on a person’s hair???
SILK
Glass Rod-
+++++--- -
Electric Charge and Static Electricity
Static electricity - the build up of electric charge due to the electrons transferring from one object to another. Electrons do not flow. Remain at rest = “static”.
Methods of Charging an ObjectII. Conduction - electrons transferred by direct contactelectrons move from one object to another.conductor—a material that allows the flow of electrons. silver, copper, aluminum, mercuryinsulator—a material that resists the flow of electrons. rubber, glass, wood
Electric Charge and Static ElectricityStatic electricity - the build up of electric charge due to the electrons transferring from one object to another. Electrons do not flow. Remain at rest = “static”.
Methods of Charging an ObjectIII. Induction - rearrangement of electrons caused by charged object placed next to neutral object. charge is “induced” when electrons move away, or attract.No contact.
ELECTRIC CHARGE
• van de graaff
http://phet.colorado.edu/en/simulation/balloons
http://phet.colorado.edu/en/simulation/travoltage
Electric Charge and Static ElectricityLaw of Charges- like charges repel, opposite charges attract
Symbol for charge is “q”Charge is measured in COULOMB’s 1 proton = 1.602 x 10-19 C1 electron = -1.602 x 10-19C
Electric Charge and Static Electricity
Coulomb’s Law – describes the electric force between any two charges, separated by a distance “r”The force of electrical attraction between two charges is directly proportional to the product of the two charges and inversely proportional to the square of the distance between them.
k = 8.9875 x 109 Nm2
C2
Many charges are expressed in micro-coulombs (C);1 x 106 C = 1 C. Easiest solution, whenever you see C, just add x 10-6 C to the number.
Ex. 5 C = 5 x 10-6 C; 28 C = 28 x 10-6 C
Coulomb’s Law Example• Two electrostatic point charges of 60 C and 50 C exert a
repulsive force on each other of 175 N. What is the distance between the two charges?
• Q1 = 60 x 10-6 C; Q2 = 50 x 10-6 C.
m0.3925d
N175
C10x50C10x60C
mN10x8.9875
d
F
QQkd
F
QQkd
QQkdFd
QQkF
662
29
21212
212
221
Electrical current is the flow of electrons. Unlike static electricity, charges are in motion.
Two types of CurrentI. Direct current (DC) - flow of electrons in one direction.car battery, flashlight batteries, photovoltaic (solar) cell
II. Alternating current (AC) - flow of electrons back and forth along a path.electric generator
Electric Current
CURRENT (I) – flow of electrons along a conductorunit: ampere (amp)1 ampere = 1 coulomb/1sec
RESISTANCE ( R ) – opposition to the flow of electrons. Electrons do work and lose energy in the form of heat.unit: ohm (Jsec/coulomb2
VOLTAGE ( V ) Potential Difference - energy available to move electrons from objects of high potential to objects of low potential energy. measures amount of work electrons can do if they move between two points. unit: volt (V) 1 volt = 1Joule/1 coulomb High voltage greater potential to do work.Low voltage less potential to do work.
Electric Current
High potential energycharged
e'e'e'
Low potential energyuncharged
OHM‘S LAW - current is dependent on voltage and resistance. It is directly proportional to voltage and inversely proportional to resistance. current = voltage resistance I = V R units: amps = volts ohms The greater the voltage, the greater the currentThe lower the voltage, the lower the currentThe lower the resistance, the greater the currentThe greater the resistance, the lower the current
Electric Current
Circuit – path, or loop, formed by a conductor that allows electrons to flow.
SERIES CIRCUIT - circuit where current travels through only one loop
PARALLEL CIRCUIT - circuit consisting of several smaller circuits connected together
Electric Circuits
Circuit – path, or loop, formed by a conductor for electrons to flow.
SYMBOLS -
Fuse - metal in a circuit which melts when current is too highCircuit breaker - metal in a circuit which bends when current is too high
Electric Circuits
conductorswitch (open)
switch (closed)power source (battery)
light bulb
resistor
flow
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