Waec 2023 Physics Question 2

(i) Connect the voltmeter to the terminals of the battery and record the voltmeter reading, \( V_{T} \). (ii) Close the key and adjust the rheostat so that the ammeter reads \( I=0.3 \mathrm{~A} \). Record the corresponding voltmeter reading \( V \). (iii) Evaluate \( I^{-1} \) and \( G=1 / L \). (iv) Repeat the experiment for four other values of \( I=0.5 \mathrm{~A}, 0.7 \mathrm{~A}, 0.9 \mathrm{~A} \) and \( 1.1 \mathrm{~A} \). In each case, record the corresponding value of \( V \) and evaluate \( I^{-1} \) and \( G \). (v) Tabulate the result. (vi) Plot a graph with \( I^{-1} \) on the vertical axis and \( G \) on the horizontal axis. (vii) Determine the slope, \( s \), of the graph. (viii) Using the graph, determine the value of \( V \) for \( G=2.5 \). (ix) State two precautions taken to ensure good results.

(i) A battery of emf 4.5K has a voltmeter connected to its terminals. If the combination is connected in series with a standard resistor and a key. It is observed that the voltmeter reading is less than \( 4.5 \mathrm{~V} \) when the key is closed. Explain the observation. (ii) An electric device draws \( 0.50 \mathrm{~A} \) in a \( 120 \mathrm{~V} \) circuit. Calculate the cost of using the device for 24 hours if the rate is \$ 0.25 per \( K W h \).