Electrical sources and internal resistance test questions

A battery is used to power the electric motor in a toy car. The battery has a measured potential difference of \(1.45V\) when the motor is not on. There is a potential difference of \(1.38V\) when the motor operates drawing a current of \(0.35A\).

What causes the drop in potential difference?

A battery is used to power the electric motor in a toy car. The battery has a measured potential difference of \(1.45V\) when the motor is not on. There is a potential difference of \(1.38V\) when the motor operates drawing a current of \(0.35A\).

Calculate the 'lost volts'.

A battery is used to power the electric motor in a toy car. The battery has a measured potential difference of \(1.45V\) when the motor is not on. There is a potential difference of \(1.38V\) when the motor operates drawing a current of \(0.35A\).

Calculate the internal resistance of the cell.

A battery is used to power the electric motor in a toy car. The battery has a measured potential difference of \(1.45V\) when the motor is not on. There is a potential difference of \(1.38V\) when the motor operates drawing a current of \(0.35A\).

The motor speeds up and draws a current of \(0.4A\).

Calculate the new terminal potential difference with the faster motor speed.

A battery has an EMF of \(4.50V\) and internal resistance of \(0.24\Omega\).

Calculate the expected terminal potential difference with an open circuit.

A battery has an EMF of \(4.50V\) and internal resistance of \(0.24\Omega\).

Calculate the expected short circuit current.

A battery has an EMF of \(4.50V\) and internal resistance of \(0.24\Omega\).

The battery is connected to a variable load and values of current and terminal potential difference are recorded and a graph plotted.

Which graph represents the variation of terminal potential difference with current?

Look at the graph of terminal potential difference against current for a battery and use the graph to determine the EMF.

Look at the graph of terminal potential difference against current for a battery and use the graph to determine the short circuit current.

Look at the graph of terminal potential difference against current for a battery and use the graph to determine the internal resistance.