WAEC 2023 Physics | Practical

(i) With no loads hanging on the metre rule, balance the metre rule horizontally on the knife edge. Record the position, G, of the knife edge on the balance metre rule. (ii) Suspend \( \mathbf{P} \) securely at \( 15 \mathrm{~cm} \) from \( \mathbf{G} \), and \( \mathbf{Q} \) securely at \( 10 \mathrm{~cm} \) from \( \mathbf{G} \). The positions of G, P and Q should not be altered throughout the experiment. (iii) Using a mass, \( m=40 \mathrm{~g} \), balance the metre rule horizontally. Measure and record the distance, \( y \), of \( m \) from G. (iv) Evaluate \( m^{-1} \). (v) Repeat the procedure for \( m=50 \mathrm{~g}, 60 \mathrm{~g}, 70 \mathrm{~g} \) and \( 80 \mathrm{~g} \). In each case, record the distance, \( y \), and evaluate \( m^{-1} \). (vi) Tabulate the results. (vii) Plot a graph with \( m^{-1} \) as ordinate and \( y \) as abscissa. (viii) Determine the slope, \( s \), of the graph. (ix) Determine the value of \( m_{p} \) given that \( 15 m_{p}=s^{-1}+200 \) (x) From the graph, deduce the mass, \( m \), that would produce a balance distance, \( y=27.5 \mathrm{~cm} \). (xi) State two precautions taken to ensure good results.

(i) State two conditions necessary for a body to be in equilibrium. (ii) Two forces \( 4 \mathrm{~N} \) and \( 3 \mathrm{~N} \) act at right angles to each other, calculate the equilibrium of the system of forces.

(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 \( K W h \).