Calculate, to three significant figures, the resistance of the wire.
The nichrome wire is included in a potentiometer circuit with a cell of e.m.f. $1.2\,\text{V}$ and negligible internal resistance, as shown in Fig. 7.1. Explain what is meant by a null method.
The nichrome wire is included in a potentiometer circuit with a cell of e.m.f. $1.2\,\text{V}$ and negligible internal resistance, as shown in Fig. 7.1. The circuit is being used to find the e.m.f. of cell X. A galvanometer is employed in a null method to locate the null point $64\,\text{cm}$ from the left-hand end of the nichrome wire.
Calculate the e.m.f. of cell X from the information given.
The cell of e.m.f. $1.2\ \text{V}$ is replaced with a new cell that has the same e.m.f. but a non-negligible internal resistance. State and explain the effect, if any, of the internal resistance of the new cell on the position of the null point.