electricity key knowledge Flashcards
what is current
rate of flow of charge
what is the formula for charge
Q = I x t
potential difference
workdone per unit charge
what is the formula linking voltage work done and charge ?
v = work done/charge
what is the formula for workdone
w = I x V x t =
what is the formula for electrical power
p = IV
what is the formula for resistance
R = V/I
what is ohms law
pd across a metallic conductor must be proportional to the current through it provided that the physical conditions do not change
advantages of using potential divider
pd and current across the component could be adjusted to 0
what is superconductor
material that has 0 resistance at or below critical temperature
uses of superconductors
MRI scans transformers
to develop power cables that transfer energy without energy dissipation
why does resistance decrease for thermistor when its temperature increases
as temperature increase more charge carriers are released more charge carriers in the circuit means that the current increases. in respect to v = ir as the current increases the resistance must decrease in order for voltage to be constant
why does metal have a positive temperature coefficient
resistance of metal increases with temperature increasing
