Waec 2025 Physics Question 3

(i) Connect the circuit as shown above leaving the key open. (ii) Close the key and adjust the meostat until the ammeter reads \( \mathrm{I}=0.20 \mathrm{~A} \). (iii) Record the corresponding voltmeter reading \( V \) (iv) Evaluate Log V and Log I. (v) Repeat the experiment for \( \mathrm{I}=0.30 \mathrm{A}, 0.40 \mathrm{A}, 0.50 \mathrm{A} \) and \( 0.60 \mathrm{A} \) for each case, record V, Log V and Log I. (vi) Tabulate the results. (vii) Plot a graph with Log V on the vertical axis and Log I on the horizontal axis starting both axes from the origin. (viii) Determine the slope, \( s \), of the graph. (ix) Determine the intercept, \( c \) on the Log I axis. (x) Calculate the value of R, in the equation \( \log R_{T}=c \) (xi) State two precautions taken to obtain accurate results.

(i) Define the term volt. (ii) A battery has an emf of 120 V and an internal resistance of \( 0.5 \Omega \). If a \( 2 \Omega \)