2022 RI Promo Sect C QP

© Raffles Institution [Turn over Name: ( ) CT Group: 23S0 RAFFLES INSTITUTION 2022 YEAR 5 PROMOTION EXAMINATION 30 September 2022 H2 PHYSICS RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION I Section C INSTRUCTIONS TO CANDIDATES Write your name, index number and CT Group. Write your answers to Section C in the spaces provided in this booklet. For Examiner’s Use Section C 21 / 15 22 / 15 There are 10 printed pages, inclusive of the cover page, in this booklet

2 © Raffles Institution 21 (a) In an experiment to demonstrate the double-slit interference pattern, parallel light of wavelength 589.0 nm from a sodium lamp is incident on a pair of slits S 1 and S 2 each of width 0.150 mm and separated by 0.450 mm. The interference pattern is observed at a screen located 2.000 m away from the slits as illustrated in Fig. 21.1. Fig. 21.1 (not to scale) At the start of the experiment, an opaque obstacle was carefully positioned in front of the double-slit system such that only the light passing through S 1 is incident on the screen. Determine the distance of the first minimum from the centre of the central bright fringe. distance = m [3] (b) The opaque obstacle is now removed so that an interference pattern is observed. (i) Determine the separation between two nei ghbouring fringes of the interference pattern. frin ge separation = m [2] 0.150 mm 0.450 mm S1 S2 yellow light (589.0 nm) opaque obstacle screen 2.000 m

3 © Raffles Institution [Turn over (ii) On Fig. 21.2, sketch the variation with distance x from the centre of the interference pattern of the intensity observed on the screen up to the fourth order maxima on both sides of the centre. [2] (c) Fig. 21.3 shows the individual waveforms from slit S 1 and slit S 2 at a point P between the zeroth order and the first order maxima of the interference pattern. (i) Using Fig. 21.3, 1. state the phase difference between the waves at point P. phase difference = rad [1] intensity Fig. 21.2 x waveform from slit S1 waveform from slit S 2 Fig. 21.3 time

4 © Raffles Institution 2. determine the ratio 1 2 intensity of wave from S intensity of wave from S at point P. ratio = [2] (ii) On the horizontal axis of Fig. 21.2 mark the approximate position of point P. Label it with the letter “P”. [1] (d) The yellow light from the sodium lamp cons ists of a second wavelength of 589.6 nm. To show the presence of this wavelength, the d ouble slit of Fig. 21.1 is replaced by a diffraction grating of 500 lines per mm. (i) Calculate the angular separation in radians of the second order maxima for the two wavelengths 589.0 nm and 589.6 nm. an gular separation = rad [2]

5 © Raffles Institution [Turn over (ii) The maxima are viewed using a telescope with an objective lens of diameter D. The telescope is placed very near to the diffraction grating as shown in Fig. 21.4. Use the Rayleigh criterion to find the approximate value of D such that the two maxima are just resolved. D = m [2] yellow light second order beams telescope diffraction grating Fig. 21.4

6 © Raffles Institution 22 Read the passage below and answer the questions that follow. Solar energy has been widely used around the world as a greener form of energy. The following passages show how it is used in three different applications: 1. floating solar farm, 2. domestic usage of solar energy and 3. solar powered aircraft. (a) In Singapore, the Republic took one big step towards environmental sustainability when its first large-scale floating solar photovoltaic (PV) system at Tengeh Reservoir - about the size of 45 football fields - was officially opened on 14 July 2021. Fig. 22.1 shows part of the floating solar farm. Fig. 22.1 The idea of building a floating solar farm came up a decade ago when Singapore was looking for ways to harness solar energy on a large scale. In 2016, national water agency PUB and the Economic Development Board launched a test bed at Tengeh Reservoir, which showed that a floating solar farm was fe asible and did not affect surrounding wildlife or water quality. The energy generated goes into the national electricity grid, providing energy for the various sectors in the country. As dirt on the solar panels can reduce operational efficiency, they are tilted at a slight angle to allow rainwater to wash the dirt off. PV cells are made of light-sensitive semi conductor materials. There are two broad categories of technology used for PV cells, namely crystalline silicon and thin film, which is a newer technology that is growing in popularity. An important differentiator in solar PV perform ance, especially in hot climates, is the temperature coefficient of power. PV cell perfo rmance declines as cell temperature rises. For example, in bright sunlight, cell temperatures in Singapore can reach over 70 C, whereas PV cells are rated at a cell temperature of 25 C. The percentage loss in power output at 70 C is therefore measured as (70  25)  temperature coefficient. Most PV cells using thin film technologie s have a lower negative temperature coefficient compared to those using crystalline silicon tech nologies. In other words, they tend to lose less of their rated capacity as temperature rises.

7 © Raffles Institution [Turn over Fig. 22.2 shows the temperature coefficient of the two PV cell technologies. Technology Temperature Coefficient (% / C) Crystalline silicon  0.50 Thin film  0.25 Fig. 22.2 The output of a PV cell is measured relative to that of a cell at Standard Test Conditions (STC) at the temperature of 25 C. Fig. 22.3 shows the variation with temperature of the relative output of a PV cell using crystalline silicon technology. Fig. 22.3 (i) State why the solar panels are tilted at a slight angle. [1] (ii) Calculate the percentage power loss of the thin film PV cells when the cell temperature reaches 70 C. power loss = % [1] (iii) Hence, sketch in Fig. 22.3, the graph to show the variation of the output of the thin film PV cells with temperature. [1] 25 35 45 55 65 75 cell temperature / C 70 80 90 100 cell output relative to STC

8 © Raffles Institution (b) In the United Kingdom (UK), domestic PV cell sy stems convert sunlight into electricity which can be used in the home. Fig. 22.4 shows the power generated P from two identical PV ce ll systems over various hours of the day. The two systems are placed at an angle of 35  to the horizontal such that one system is East