current electricity 💱 Flashcards
define current
current is the rate of flow of electric charge
current formula
I = Q / t
define electromotive force (emf)
emf is the work done by an electrical source in driving a unit charge around a complete circuit
define potential difference
potential difference across a component is the work done to drive a unit charge through the component
emf / pd formula
E = W / Q or V = W / Q
define resistance
resistance of a component is the ratio of the potential difference across it to the current flowing through it
resistance formula
R = V / I
resistance of a wire formula
R = p L / A
state ohm’s law
the current flowing through a metallic conductor is directly proportional to the potential difference across it, provided physical conditions like temperature remain constant
why is a filament lamp a non-ohmic conductor?
as current increases, more heat is generated and temperature increases, increasing the resistance of the lamp
