Emf and Internal Resistance

Internal resistance (r)

The resistance inside a battery from electrons colliding with atoms inside the battery

Load resistance (R)

The total resistance of all the components in the external circuit

What is the load resistance sometimes also called?

External resistance

emf

The amount of electrical energy the battery produces and transfers to each coulomb of charge

What does emf stand for?

Electromotive force

In a series circuit, if two cells are connected negative to negative, what happens to the emfs?

They cancel out

What is terminal pd? (simple)

The pd across the load resistance

What is terminal pd?

The energy transferred when one coulomb of charge flows through the load resistance

What would be the case if there was no internal resistance?

Terminal pd = emf

Lost volts (v)

The energy wasted per coulomb overcoming the internal resistance

emf equations

ε = I(R + r)

ε = V + v

What does the conservation of energy tell us for any electrical circuit?

energy per energy per coulomb energy per coulomb

coulomb supplied = transferred in load + wasted in internal

by the source resistance resistance