Electricity Flashcards
Electromotive force
The amount of energy supplied to each unit charge when a form of energy is transferred to electrical energy
Potential difference
Work done per unit charge
Current
Rate of flow of charge
Electromotive force equation
EMF = energy / charge
e=w/Q
Conventional current
Current flowing from positive to negative
Electron flow
Electrons flowing from negative to positive
Resistance
Potential difference across a component divided by current
Kirchoff’s first law
The sum of the current entering a junction is always equal to the current exiting the junction
Mean drift velocity
Average velocity of the electrons as they travel down the wire
What’s the value of an electrons charge
-1.6 x 10^-19
What is and how do you work out charge carrier density
Number of electrons in 1m^3
1/d^3
Conductors and insulators
Conductors - large no. of free conduction electrons per unit volume
Insulators - low no. of free conduction electrons (poor conductors)
Semi-conductors
Intermediate conduction properties , a value of n between conductors and insulators
n = (number density)
What happens when you increase temp on a semi-conductor
Electrical conductivity increases due to overcoming energy barrier
Coulomb
Amount of charge passing a point in a second when the current is 1A
