Electricity revision Flashcards
Define electric current
Rate of flow of charge
What is the unit of charge
Coulomb
What is e
elementary charge = 1.6 x 10^-19
Why is net charge on a partice in terms of e
electrons are a fundemental particle
How does current move in metals an electrolytes
In metals current flows as the movement of electrons
In electrolytes current flows as the movement of ions
What is the difference between conventional current and electron flow
Conventional current = Flow from positive to negatiove terminal
Electron flow = Flow from negative to positive terminal
Kirchoffs 1st Law
Conservation of charge. The sum of currents flowong into a junction is equal to the sum of currents flowing out of the juction
What is mean drift velocity of charge carriers
Measure of the average distance they travel per unit time in the direction of the force
What is the equation for I (n is the number density of charge carriers
I = Anev
What is a conductor in terms of n
10^28 free electrons per cubic meter (high number density)
What is a semiconductor in terms of n
10^17 free electrons per cubic meter
What is an insulator in terms of n
Very low number density
Define p.d
Measure of the transfer of energy by the charge carriers.
what is emf and how can it be used to describe a source
Measure of the transfer of energy to the charge carriers (the greater the emf the more energy per coulomb has been transferred into electrical energy)
What is emf measured in
Volts
