M4.1 electricity Flashcards
define current
the rate of flow of electrons
define colomb
unit of charge
1 coloumb is the amount of charge that passes through 1 second at 1 amp
what is charge carrier
any charged particle electron is the smallest charge carrier
what makes a good conductor a good conductor
it has a high number of charge carriers per unit volume
define mean drift velocity
electrons dont always go straight from negative to positive however they tend to drift from negative to positive.
define potential difference
work done per unit charge
amount of energy transferred per unit charge
think about it like needing energy to push the electrons (like 9J energy used on each coloumb of charge in a 9V system)
what is the kinetic energy in of the electrons
kinetic energy is equal to work done
equation of work done for one electron
W = eV
what is kirkovs first law
current into a junction is equal to current out of the junction
what is kirkoff’s second law
The voltage accrosss each component is equal to the voltage accross the cells
what does resisitance decide
the amount of current per unit voltage
what are the three main things that effect resistance
length
cross sectional area
resistivity
(temperature)
how do semi-conductors work
have some free moving electrons have some locked in place
can be unlocked with a certain condition i.e thermistor can be removed with temperature or light with LDR
what equation to use when talking about energy wasted
P = I^2 * r
(maybe another if you have to use the other power equation that uses resistance)
what is the national grid
a network of cables that transfers electricity from power station to consumer
