CURRENT ELECTRICITY- ___________________We are reasonably familiar with some aspects of hooking up electrical circuits as most of us have connected wires, batteries and light bulbs.

Words associated with electricity include:

 

  

 

 

 


Let us go over real basics. To make "something" (refrigerator, light, computer, radio controlled car, cell phone......) turn on we need an appropriate source of electricity, metal wires insulated with plastic, a switch and the thing.

The source is________________________.

The energy is transferred to the globe or CD player where it changes to _______or _________or ___________or ______________- all forms of energy. But why is it necessary to have two wires? Surely the transfer can take place with only one wire? The answer lies in the method of transfer - the motion of electrons from high potential energy in the source to low potential energy in the source. 

Because it makes a continuous loop, we call the arrangement a circuit.

The flow of electrons is called a______________, an electric current. They flow from high to low energy in response to an__________________.  Like charges repel. That is precisely what is happening in the circuit, negative electrons are being repelled from the "negative terminal" of the source and subsequently attracted to the positive terminal. The source uses energy from some other means to keep the electrons flowing.

 
VOLTS:

Volts ___________are used to measure the potential difference.  Most small modern batteries are supposed to be 1.5 or 9 volts. A car battery is slightly over 12 volts. Our houses have 120 V.  Without a__________________         _______________, there will not be a flow of electrons.   Voltage can be considered the _______or _____________ of electrons. Voltmeters measure volts.

Voltage sources :  ______________, _________________,_________________

 

 Electrochemical cells changes _______________________________________.

 

 

basic parts of a wet cell

basic parts of a dry cell

 
ELECRIC CURRENT:

 Electric current is the amount of Charge that passes a point per second.

 Symbol-                                      SI unit – ampere

 Ammeters measure amps. 

Current Direction:

 

______________, AC: basic parts of a commercial power plantAC is produced by a______________.

 

 

RESISTANCE:

Opposition to electric flow is called resistance.  Resistance is caused by _____________________.

 Symbol is R.

Unit is OHM (           ).

Electric charges are slowed down by interactions with atoms in the wire.

Resistance depends on type of material

 

Resistance _____________________the current flow. 

Tungsten Lightbulb-

 

Variables _________________, ________________, ____________________

Conductivity depends on __________________________the electrons are held in the atoms.

 

SuperConductors-

 

A  poorly conducting wire (light bulb) is said to provide ___________________in the circuit. This resistance property controls the electron flow or current.

HIGH resistance tends to mean ____________currents, LOW resistance tends to mean _____________currents for a given potential difference.

(The ultimate in high resistance is a break in the circuit, an OPEN circuit)

 

 

Emergency switch:

circuit breaker

 

 

 

 


 
 

 

Ohmís Law- Current = Voltage/Resistance

 

 

 

 


 
     Electric circuit: A complete, _____________path for an electric current.

_____________                 

A series circuit with only one path for current flow.
There is only one path for the electrons to take. Current is the _________

 

__________

 


There is more than one path for the electrons to take.

A parallel circuit with two paths for current flow.

Schematic diagrams

Electric power: A measure of the rate at which electricity does ______________ or provide energy.

 

 

 

 

 

 

 

Power = Voltage X Current

Watts = Volts X Amperes