A student is asked to compare the e.m.f.s of a standard cell and a test cell. He sets up the circuit shown using the test cell.

(a) (ii) State how he would recognise the balance point.

A student is asked to compare the e.m.f.s of a standard cell and a test cell. He sets up the circuit shown using the test cell.

He achieves balance when the distance $\mathrm{AB}$ is $22.5 \mathrm{cm}$. He repeats the experiment with a standard cell of e.m.f. of $1.434 V$ The balance point using this cell is at $34.6 \mathrm{cm}$. Calculate the e.m.f. of the test cell.

When a cell is connected in series with a resistor of $2.00\Omega$ there is a current of $0.625 \mathrm{A}$. If a second resistor of $2.00\Omega$ is put in series with the first, the current falls to $0.341 \mathrm{A}$. Calculate:

The internal resistance of the cell

When a cell is connected in series with a resistor of $2.00\Omega$ there is a current of $0.625 \mathrm{A}$. If a second resistor of $2.00\Omega$ is put in series with the first, the current falls to $0.341 \mathrm{A}$. Calculate:

The e.m.f. of the cell.

 A car battery needs to supply a current of $200 \mathrm{A}$ to turn over the starter motor. Explain why a battery made of a series of cells of the type described $\mathbf{b}$ would not be suitable for a car battery.

State what is meant by the term e.m.f. of a cell

A student connects a high-resistance voltmeter across the terminals of a battery and observes a reading of $8.94 V$ He then connects a $12\Omega$ resistor across the terminals and finds that the potential difference falls to $8.40 V$.

Explain why the measured voltage falls.

A student connects a high-resistance voltmeter across the terminals of a battery and observes a reading of $8.94 V$ He then connects a $12\Omega$ resistor across the terminals and finds that the potential difference falls to $8.40 V$. Calculate the current in the circuit.