Section 1 - Electricity Flashcards
Current
The rate flow of charge
Potential difference
The work done per unit of charge
Mean drift velocity
The average velocity of charge carriers
Resistance
The opposition that a substance offers to the flow of electric current
Resistivity
The measure of the resistance of a given size of a specific material
Ohmic conductors
Conductors which follow ohms law. The current is directionally proportional to the potential difference
Number density
The number of free electrons per cubic metre of material
Electrical power
The rate of energy transfer
Kirchhoff first law
The sum of the currents into a junction equal the sum of the currents out of the junction
Kirchhoff second law
The sum of the emf equals the sum of the potential difference around a closed loop
Potential dividers
Used to divide the potential difference to give any value you require up to the maximum supplied from the power source
EMF
The total amount of work the battery does on each coulomb of charge
I-V characteristic of a metallic conductor
A straight line. Current is proportional to Potential difference
I-V characteristic of a filament lamp
A curved line. The current increases its temperature, increasing its resistance
I-V characteristic of a thermistor
A curved line. The current increases its temperature, increasing its potential difference
