Electricty Flashcards
A.C.
Alternating current
D.C.
Direct current
Rms means
Root mean square
Ipk
Peak current
When in series, current is
The same everywhere
( Series)The total resistance is the
Sum of all the resistors
(Series) The sum of the voltages across the resitistirs is
Equal to the supply voltage
(Parallel) the voltage across each component is
The same
(Parallel) the supply current is equal to
The current in all branches
I
Current
r
Internal resistance
What do capacitors do?
Store charge
Unit of capacitance
Farads (F)
Increasing the resistance in a capacitor circuit
Increases the amount of time for it to charge
Conductor
Lets electricity flow
Insulator
Does not conduct electricity
Semiconductor
Conducts electricity but not very well
Conduction requires electrons that are
Free to move
In single atoms, electrons can only occupy
Specific energy levels with gaps in between
When atoms combine to form solids,
Energy levels become wider but still with gaps in between
Outer electrons are found in the
Valence band
In an insulater, the valence bands are
Full
In an insulater the next band above the valence band is the
Conduction band
(Insulator) If a lot of energy is given to electrons (extreeme conditions) they can
Move to the conduction band and electrified conduction can now take place
The gap between the valence and conductor bands in a semiconductor is
Small/narrow
Electrons in conductors are
Partially free to move
In a conductor, the valence band will
Be partially full or the conductor and valence band will overlap
Doping
The adding of impurities to semiconductors to improve conductivity
N-type
Negative charge carriers
P-type
Positive charge carriers
P-n junction
Electrons in n-type fill holes in the p-type so an electric field exits across the junction in the depletion layer
Reverse bias
The p-n junction is connected and the cell strengthens the electric field and charges move further apart increasing the depletion layer
What conduction takes place in reverse bias
No conduction
Does conduction takes place in forward bias
Yes
Forward bias
The cell overcomes the electrons the exist across the junction.
Light emitting diode
An electron falls into the whole and a photon of light is released
Solar cell
Energy of a photon lifts an electron from the valence band to the conduction band, electric field moves then causes potential difference
