Question 3

 

 

 

 

In the set up above, a constantan wire of length, l = 3 cm is connected to an ammeter, A2, whose current reading is I.

With the key close and the resistance box set at R Ω, the ammeters, A1and A2, show current reading I and Irespectively with the voltmeter showing a reading V.

The experiment was repeated for four other values of R with corresponding values of IIiand V recorded in each case.

The diagrams shown shown in Fig. 3(a) below shows the values of Ri  offered in the circuit by the Rhetostat, Rh, while Fig. 3(b)and Fig. 3(c) shows the corresponding values of IiandIireadings from the ammeters, A1and A2, respectively, where  = 1, 2, 3, 4 and 5.

The corresponding voltmeter readings Viis shown in Fig. 3(d)where i = 1, 2, 3, 4 and 5 respectively.

(iv)       Measure and record Vo, also measured and record V1 where i = 1,2,3,4 and 5 corresponding to the values of  Ri already read and recorded and convert Voand V1 to real values, V, using the scale provided.
(v)        Tabulate your readings

(vi)       Plot a graph of  Io on the vertical axis  and V on the horizontal axis.

(vii)      Determine the slope, s, of the graph.

(viii)     Determine the intercept, C, on the horizontal axis.

(ix)       State any two precautions necessary to ensure accurate results when performing this experiment.

            (b)        (i)         State three factors that determine the choice of a wire as a conductor.
(ii)        Write the expression to determine the resistivity, ρ, of a constantan wire of cross-sectional area, A, resistance, R and length, L.