See diagram above Adjust frequency until the paper rider falls off (resonance occurs) Record the frequency on the signal generator and measure the length between the bridges. Adjust the distance between the bridges and repeat. Because frequency also depends on tension and you can only investigate the relationship between two variables at a time. 1/l (m− 1) 2.00 3.03 4.00 5.00 6.02 7.04 8.00 See graph Fundamental frequency is inversely proportional to length Arrangement: see diagram above vibrating fork placed on bridge adjust length until resonance occurs /rider falls measure length (between nodes / bridges) repeat with forks of different frequencies 1/length 1.66 1.81 1.99 2.21 2.48 2.83 3.30 3.95 Tension: Frequency is proportional to the square root of tension. Mass per unit area: Frequency is proportional to 1/√μ Find resonance for a fork f by changing tension Method for changing/measuring tension // keep l fixed Repeat for forks of different frequencies INVESTIGATION OF THE VARIATION OF FUNDAMENTAL FREQUENCY OF A STRETCHED STRING WITH TENSION [2004] A student investigated the variation of the fundamental frequency f of a stretched string with its length l. Draw a labelled diagram of the apparatus used in this experiment. Indicate on the diagram the points between which the length of the wire was measured. The student drew a as shown, using the data recorded in the experiment, to illustrate the relationship between the fundamental frequency of the string and its length. State this relationship and explain how the graph verifies it. The student then investigated the variation of the fundamental frequency f of the stretched string with its tension T. The length was kept constant throughout this investigation. How was the tension measured? What relationship did the student discover? Why was it necessary to keep the length constant? How did the student know that the string was vibrating at its fundamental frequency? [2009] A student investigated the variation of the fundamental frequency f of a stretched string with its tension T. The following is an extract of the student’s account of the experiment. “I fixed the length of the string at 40 cm. I set a tuning fork of frequency 256 Hz vibrating and placed it by the string. I adjusted the tension of the string until resonance occurred. I recorded the tension in the string. I repeated the experiment using different tuning forks.” How was the tension measured? How did the student know that resonance occurred?
Smooth curve Good distribution Range: 28↔ 32 Ω (0C–1) or Ω (K–1) Oil is a better conductor of heat / water contains air / (impure) water conducts electricity/good thermal contact TO INVESTIGATE THE VARIATION OF CURRENT (I) WITH POTENTIAL DIFFERENCE (V) FOR A THIN METALLIC CONDUCTOR [2013] A student was asked to investigate the variation of current with potential difference for a thin metallic conductor. The student set up a circuit using appropriate equipment. The student recorded the values of the current I passing through the conductor for the corresponding values of potential difference V. The recorded data are shown in the table. V/V 1.0 2.0 3.0 4.0 5.0 6.0 I/A 0.17 0.34 0.50 0.64 0.77 0.88 Draw and label the circuit diagram used by the student. Name the device in the circuit that is used to vary the potential difference across the conductor. how the student used this device to vary the potential difference. Use the data in the table to draw a graph on graph paper to show the variation of current with potential difference. Use your graph to find the value of the resistance of the conductor when the current is 0.7 A. Explain the shape of your graph. 1. apparatus: p.s.u. / battery, ammeter, voltmeter ammeter in series with conductor voltmeter in parallel with conductor Variable p.s.u. / variable resistor (rheostat) / potential divider the dial, moved the sliding contact See V ≈ 4.5 V (when I = 0.7 A on graph) R ≈ 6.4 Ω Resistance (of conductor) increases with increasing temperature Or appropriate reference to Ohm‟s law and to resistance TO INVESTIGATE THE VARIATION OF CURRENT (I) WITH POTENTIAL DIFFERENCE (V) FOR A FILAMENT BULB [2011 OL] The diagram a circuit used to investigate the variation of current with potential difference for a filament lamp. Name the instrument X. What does it measure? Name the component Y. What does it do? The table shows the values recorded for the current and the potential difference during the investigation.