Electricity - Internal resistance (topic 1)

Kirchoff’s current law

the sum of the currents entering any point in a circuit is equal to the sum of the currents leaving that point (a consequence of the conservation of charge)

Kirchoff’s voltage law

in any closed loop in a circuit, the sum of the electromotive force in the loop is equal to the sum of potential difference around that loop (a consequence of the conservation of the energy)

KVL rules

-for voltage: potential difference is positive if going from negative terminal to positive terminal vice versa

-for resistors: potential difference is negative if going with the current vice versa

terminal voltage formula

VT=E-IR

emf

the voltage across the battery when no current is drawn

graph readings

emf: y-intercept

internal resistance: gradient