I want the percent uncertainty and justifi the answer for (t)

You may not need to use all of the materials provided. For (c) Fold the sheet of tracing paper in half four times so that you have 16 layers. In this question you will investigate how the light detected by a light-dependent resistor (LDR) Examiner's For Use Examiner's depends on the thickness of an absorber. (i) Measure the thickness of these 16 layers. Use (a) (i) Connect the circuit shown in Fig. 2.1. The light-emitting diode (LED) should be 1.5 +0.20 connected the right way round so that light is emitted. = 1.70 1. 70 mm thickness of 16 layers = ...................................... (ii) Estimate the percentage uncertainty in this measurement. Show your working. LED LDR percentage uncertainty = ......... (iii) Determine the thickness t of one layer of tracing paper. 16 = 1. 70 mm Fig. 2.1 I X ? *= 0. 10625 (ii) Use the black paper and the Sellotape to make a cylinder of length 4cm. The cylinder should fit neatly over the LDR. 16 x = 1.70 mm 21 : 1.70 mm 0. 11 mm (iii) Cut the cylinder in half so that you have two cylinders of length 2cm. 16 (iv) Justify the number of significant figures you have given for t. Tape one cylinder over the LDR and the other cylinder over the LED as shown in Fig. 2.2. Sellotape Sellotape LED 2 cm 2 cm Fig. 2.2 (b) Place the cylinders together, as shown in Fig. 2.3. Record the voltmeter reading V. 2. 6 5 V Fig. 2.3 Vo = .. ........... ................................ UCLES 2008 UCLES 2008 [Turn over 9702/31/M/J/08 9702/31/M/J/08