10.4 Internal Resistance

Question 1

What is internal resistance?

Answer 1

Internal resistance is the set amount of resistance within a cell or battery. It causes the actual amount of energy to be less as some is lost as heat. It can be calculated in the equation:
ε = Ir + V
where ε is the electromotive force, I is the current, r is the internal resistance and V is the terminal p.d. Ir combined is known in the equation as lost volts as it gets transferred into thermal energy. This equation can be rearranged to get:
V = ε - Ir
or
ε = Ir + IR
where R is the resistance of the circuit (IR can be substituted from the equation V = IR).