CAIE
Physics
(9702)
Questions & Answers
Record the voltmeter reading E.
Set up the circuit shown in Fig. 1.2. The distance between F and G is L. Attach F and G to the wire so that L is approximately 30 cm. Close the switch. Record the value of L and the voltmeter reading V. Open the switch.
Write down the value of E from (a). Increase L by changing the position of F on the wire. Record L and V and repeat until you have six sets of values of L and V. Include your values from (b). Record your results in a table. Include values of (E - V) / L in your table.
Plot a graph of (E - V) / L on the y-axis against V on the x-axis.
Draw the straight line of best fit.
Determine the gradient and y-intercept of this line.
It is suggested that the quantities V and L are related by the equation (E - V) / L = PV - Q, where P and Q are constants. Using your answers in (d)(iii), determine the values of P and Q. Give appropriate units.
The resistance of R is R. Theory suggests that P and Q are both inversely proportional to R and the graph cuts the x-axis at a value of V = E/2 for all values of R. A student repeats the experiment using two identical resistors, each with a lower value of R than in the original experiment. For the student’s experiment, draw a second line on the graph to show the expected results. Label this line W.
The diameter of the smaller sphere is d, as shown in Fig. 2.1. Measure and record d.
Estimate the percentage uncertainty in your value of d. Show your working.
Set up the apparatus as shown in Fig. 2.2. Ensure that the rods are the same height above the bench. Slide the paper clips at the ends of the chain onto the rods. The distance between the centres of the rods is x. Position the stands so that x is approximately 70 cm. Measure and record x.
Use the hook to attach the smaller sphere of modelling clay to the chain of paper clips as shown in Fig. 2.3. The number of paper clips between the hook and the end of the chain is n, as shown in Fig. 2.3. Place the hook so that n is 11. Calculate N, where N = n/23. Give your answer to three significant figures.
Pull the sphere towards you through a short distance. When the sphere is released, it will oscillate. Take measurements to determine the period T of these oscillations.
Roll the two spheres into one larger sphere. Measure and record the diameter d of the larger sphere. Repeat (b) and (c) with a value x of approximately 80 cm and with the hook placed so that n is 7. Record x, N and T.
It is suggested that the relationship between T, d, N and x is T^2 = kdN/x^2, where k is a constant. Using your data, calculate two values of k.
Justify the number of significant figures that you have given for your values of k.
It is suggested that the percentage uncertainty in the values of k is 15%. Using this uncertainty, explain whether your results support the relationship in (e).
Describe four sources of uncertainty or limitations of the procedure for this experiment. For any uncertainties in measurement that you describe, you should state the quantity being measured and a reason for the uncertainty.
Describe four improvements that could be made to this experiment. You may suggest the use of other apparatus or different procedures.