Download Electricity guided notes

ELECTRICITY
ELECTRIC CHARGES
Atoms are composed of _________ main parts. _______________, p+, positive, located in the nucleus;
________________, no, neutral, located in the nucleus; ____________________, e- , negative, located
outside the nucleus in the electron cloud. Everything is made of ________________.
Protons and electrons have a property called _________________________. An atom has __________
numbers of positive and negative charges so they _________________ each other out. Electrons can
__________ from one atom to another atom. This movement is called ____________________.
STATIC ELECTRICITY
Some atoms hold their charges more ____________. Latin word “stasis” which means ___________.
Static electricity is the ______________________ building up of charge on an object. Protons _______
move. Only _______________ move. In static electricity, the charges ___________________________
– they do not _________. When you walk across a carpet, __________________ causes electrons to
move from the carpet to your shoe. This is a build-up of static electricity. You ____________________
the electricity by touching a _________________________.
LAW OF CONSERVATION OF CHARGE
When an object becomes charged, the electric charge is _______________________________________
– it just ________________ from another object. Static electricity is an ______________________ in
the amounts of positive and negative charges on the surface of an object.
Another way to generate static electricity is with a ______________________ generator. American
physicist Robert Jemison Van de Graaf invented the Van de Graaf generator in 1931.
There are _____________ ways to charge on object:
1. Charging by ______________ - The charge is transferred because of rubbing two objects
together. Example: shoes on a carpet
2. Charging by ______________ - Involves the charging of one object by another object
_______________________ direct contact. Example: balloon and rice cereal/electroscope
3. Charging by ______________ - Involves the ________________________________ of a
charged object to a neutral object. Example: Van de Graaf generator
Objects do not hold a static charge ________________ – objects tend towards ____________________
– they want to be neutral. When electrons move toward this equilibrium – static discharge occurs.
-
__________________ – water (a polar molecule) vapor in the air pulls electrons off
negatively charged objects, preventing static charges to build up.
-
_______________________________ - objects reaching static equilibrium
CONDUCTORS
Allow the _______________________ of electricity; loosely bound electrons that are free to move from
atom to atom. Examples:
INSULATORS
Insulators – ___________________ the flow of electrons; hold more tightly to their valence electrons.
Examples:
ELECTRIC CURRENT
Define:
REMEMBER:
Conductors let electrons move ____________. Insulators do ________ let electrons move easily. A
_________________________ has conductivity somewhere between an insulator and a conductor.
Devices made of semi-conductors, notably _____________________, are essential components of most
electronic circuits.
There are __________ parts to an electric charge
1. ___________________ - For electrons to flow there must be a ___________________________
between two places. This is called voltage which is the ___________ that causes electrons to
flow. It is ____________________________. Charges flow from ________ voltage to _______
voltage. Units: ________________________
2. ___________________ - The measure of _________________________ per second are flowing
through the wire is the amperage. Units: _________________. The number of electrons
flowing per _________________. Electrical current is like the amount or __________________
_______________ flowing through the hose. There are two types of current: AC – __________
current and DC – ____________ current.
3. ____________________ - The tendency for a material to ______________ the flow of electrons.
___________________ materials have ___________________ amounts of resistance to the flow
of electrons. Units: __________________. Examples: ___________, ____________, and
_____________ have low resistance, which means that current can flow _____________ through
these materials. __________, _____________, and __________ have very __________
resistance, which means that current ______________ pass through these materials easily.
_________ wires provide more resistance than do _________ wires. Resistance in wires
produces a _________ of energy (usually in the form of __________), so materials with no
resistance produce no energy loss when currents pass through them. Resistance also depends on
______________________, usually increasing as the temperature ___________________.
OHM’S LAW
In a material, the current (I) is ________________ proportional to the voltage (V) and
____________ proportional to the resistance.
Water in a Hose
DC in a Wire
Voltage (potential) (V)
Electrical Units
Current (I)
Resistance (R)
PRACTICE
What is the current produced with a 9-volt battery through a resistance of 100 ohms?
BATTERIES
TWO TYPES:
1. ___________ Cell – the electrolyte is not really dry; but is a paste.
–
Standard AA, C, D type batteries, electrolyte is a paste. The “+” terminal is carbon.
2. ___________ Cell – the electrolyte is a liquid (car battery)
–
In a car battery, the electrolyte is sulfuric acid.
Batteries have three parts: a _____________ (+), an _____________ (-), and an __________________.
The cathode (________________) and anode (________________) at either end of a traditional battery
are hooked up to an electrical circuit. The chemical reactions in the battery causes a ________________
of electrons at the anode. This results in an electrical ___________________ between the anode and the
cathode - an ___________________ build-up of the electrons. The electrons wants to ______________
themselves to get rid of this difference. They do this in a certain way. Electrons _____________ each
other and try to go to a place with ___________________ electrons.
ELECTRICAL CIRCUIT
Define:
Four Parts: 1. Energy Source, 2. Load, 3. Wires, 4. Switch
OPEN CIRCUITS – pathway is ___________. CLOSED CIRCUITS – pathway is ________________.
SERIES CIRCUIT
Provides only _________ path for the electrons to follow. A break in the circuit _________ the flow of
electricity to all other parts of the circuit. With multiple light bulbs (more resistance) the current
______________ and the lights become ________________. Ammeters should be wired in series.
RULES: 1. The _____________ current flows through each part of a series circuit. 2. The _________
resistance of a series circuit is equal to the ___________ of individual resistances.
PARALLEL CIRCUIT
The different parts of the circuit are on _______________ branches. A break (like a burned out light
bulb) in the circuit ___________ stop the flow to the remaining devices. Multiple light bulbs will
remain the __________ brightness since the resistance is ________ decreasing as it does in a series
circuit. Each pathway can be separately ____________________ without affecting the others.
Household circuits – Wired in ________________, with a standard of 120 volts. Voltmeters are wired
in parallel. The ____________ paths, the _____________ the resistance. Water example again: added
pipes coming from a large tank will allow ___________ water to flow out that a single pipe. Therefore
as resistance _________________, current __________________; they are inversely proportional.
RULES: 1. Voltage is the __________ across each component of the parallel circuit. 2. The _________
of the currents through each path is equal to the ____________ current that flows from the source.
Question: What is the major difference between a series circuit and a parallel circuit – in your own
words:
SCHEMATIC DIAGRAMS
All circuit drawings need at least the following: __________________, ______________________,
__________________, ___________________, other items include connectors, meters, etc. There is a
set of standard symbols used to represent these items in a diagram of the circuit.
LIGHT BULB - Electricity flows through the circuit. If the bulb is _______________, so is the circuit.
TRANSPORTING ELECTRICITY - A _____________________ is a device that increases of
decreases alternating current generated by a power plant so it can enter homes safely.
ELECTRICAL POWER - The ______________ at which electrical energy is transferred by an electric
circuit. Use Joule’s Law: Power = ________________ x ________________. Unit: ____________. A
___________________________ is what the power company uses to determine how much electricity or
energy you used. Energy used = ______________ (kW) x __________ (hours) or E= P x t. To find
cost, you would multiply the _______________ by the ________________ per kilowatt hour.
PRACTICE
1. 105 V are used to power an appliance that needs 15.0 amps. What is the power used?
Power = current x voltage.
2. How much energy is used when this appliance is used for 30.0 days, 24hrs a day?
Energy = Power x time.
3. If the power company charges 8¢/Kw-h, what is the cost of the energy above?
Cost = Energy x price per kW hr.