E.M.F and Internal Resistance

What is internal resistance

The electrons colliding with the ions in the battery

What is external or load resistance

The total resistance of all the components in the external circuit.

What does E.M.F stand for

Electromotive force

What is E.M.F

The total amount of work the battery does on each coulomb of charge

What is the terminal potential difference

The potential difference across the load resistance

What is lost volts

The energy wasted per coulomb overcoming internal resistance.

What is an equation for lost volts

E.M.F = terminal potential difference + lost volts

How do you calculate the total E.M.F in a series circuit

Add them together

How do you calculate the total E.M.F in a parallel circuit

The E.M.F is equal to whichever branch it passes through. So if each cell has the same E.M.F it does not change.

How do you get the internal resistance from a practical

Have a variable resistor on it’s highest resistance and record the potential difference and current across it. Repeat with lower values of resistance. Plot an I-V graph and calculate the gradient. Then multiply by -1.

How is the equation rearranged in a practical to find internal resistance graphically

V = -r (I) + E.M.F