Electricity Summary Flashcards
Positive ion
Lost an electron
Negative ion
Gained an electron
We charge insulators by
Friction, resulting in a transfer of electrons
Law of electrostatics
Like charges repel
Opposite charges attract
Electrons wanting to go to earth
Will go through you to the ground - give an electric shock
Insulator
Does not allow current to flow
Current defenition
Rate of flow of charge/electrons
Equation for current
Curreny(I) =charge(Q)(C)
—————
Time (t) (s)
YOU can have a ____ w/out a ______
Cannot have a _______ w/out something I.e. _________ pushing
Voltage (push)
Current
Current
Voltage
Voltage def:
Measure if work done by cell/ battery as current flows through circuit
Current/voltage/resistance
SERIES
Current - same
Voltage - shared
Resistance - added
Current/voltage/resistance
PARALLEL
Current - shared
Voltage - same
Resistance - added
Def resistance
Opposition to flow of charge
Voltage equation
Voltage = current x resistance
Thermistor:
Resistance drops as current/temp. increases
Graph is top left to bottom right curve to origin
LDR
Light dependent resistor Resistance drops as light increases Light goes up Resistance goes down Current goes up
Resistor
For same temp. then ohms law applies - voltage is directly proportional to current;;; v=i x r
Lamp
As current flows the wire heats
Causes res. To increase
Start slow the increase of current
Particles gain energy and vibrate more, obstructing current path
Diode
Allows current to flow in one direction only
High resistance in reverse and low in forward
National grid
System of transformers and cables
Transformer
Can step up or down voltage
Used in national grid to increase efficiency
Main voltage
+- 230V - alternates back and forth
50Hz (frequency)
Plug cable
Earth wire: safety: green/yellow
Live wire: brown: energy in
Neutral: completes circuits: blue
Electrical power equation
P=i x v —> p= v x Q x t
Energy: e= p x t
E= v x Q
P= I(2) x r
