Browsing by Author "Chandana, A.W.S."

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    Design of an Inexpensive Digital Watt-hour Meter
    (2003) Chandana, A.W.S.; Wijesundera, R.P.; Jayasuriya, K.D.; Kalingamudali, S.R.D.
    An inexpensive digital watt-hour meter has been designed and tested using MCap 7 simulation package since commercially available digital watt-hour meters are very expensive. One of the major usages of watt-hour meters is to measure the power consumption of electricity consumers for billing purposes. Although digital watt-hour meters are commercially available,all electrical power supply companies through out the world including well-developed countries like the United States ofAmerica and the United Kingdom use analogue watt-hour meters to measure the power consumption. This is probably due the expensiveness ofdigital watt-hour meters. The designed digital watt-hour meter consists with analogue multiplier, analogue to digital converters, adder, registers, digital clocks, dividers, accumulators and digital displaying unit. Basically the current and voltage will be multiplied by using a four-quadrant analogue multiplier and then converted to digital signals using analogue to digital converters, which is clocked at a frequency significantly higher than mains frequency, to produce instantaneous values. The algebraic average of the output product per second will be the power consumption per second Finally, this will continuously be added and sent to the digital displaying unit to display watt-hour output. One of the major advantageous of the digital walthour meter is that the power consumption cannot be tampered like in analogue watt-hour meters where the power consumption can be very easily disturbed by changing the rotation power ofthe rotating disk.
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    An experiment on interference
    (Research Symposium 2009 - Faculty of Graduate Studies, University of Kelaniya, 2009) Chandana, A.W.S.; Siripala, W.; de Silva, N.
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    Experiments on interference
    (University of Kelaniya, 2008) Chandana, A.W.S.; Siripala, W.P.; de Silva, N.
    We report a few experiments carried out to demonstrate the formation of interference patterns with thin Aluminium sheets placed along zero probability positions (positions where the probability of finding a particle is zero). The presence of the Aluminium sheets did not destroy the interference patterns though one would have expected the particles to interact with the sheets and wash out the patterns. In the experiment arrangement, Laser beam (He/Ne gas laser, wave length 633nm, maximum power <1mW ), a double-Slit (a= O.lmm, b = 1mm), digital camera, Aluminium sheets (0.056cm x 3cm x 40cm), two lenses and traveling microscope were needed. Eight thin Aluminium sheets of dimensions 0.56cm x 3cm x 30cm were placed along zero probability positions within the central maxima of interference pattern, and 20 more thin small Aluminium sheets of dimension 0.056cm x 3cm x 6cm were paced along zero probability positions of the diffraction pattern. The interference patterns were not changed as can be seen in the figure 1 Now the front edge of the first Aluminium sheet from the left of the eight sheets that were placed within the central maxima was moved through 4mm without moving the rear end of the sheet. The diffraction and interference patterns were washed off as shown in the figure 2.
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    Some Experiments Involving Double- Slit
    (University of Kelaniya, 2007) Chandana, A.W.S.
    We present patterns obtained when photons were made to pass through double slits improving on results obtained by Afshar1•2 though in a different context. Laser beam was passed through the double-slit with or without the wire grids 1 and/or 2 as the case may be. screen leaser source double -slrr wire grig 01 wire grid 02 ~,...._.......,.CI -------. optical bench Ag (01) Laser beam was made to pass through the double and strike the screen. Following pattern (Fig 02) was seen on the screen. The distance between the double slit and the screen was 430cm. Fig (02) Then wire grid 02 (radius 0.4mm, height 4cm) was placed at the zero probability positions of the pattern at 424cm from double-slit. However the pattern was not changed as seen in Fig (03). This is the essence of experiments carried out by Afshar. 133 Proceedings of the Annual Research Symposium 2007- Faculty of Graduate Studies. L'ni1·ersily of Kelaniya Fig (03) Another wire grid (0 1) was placed at the zero probability position of the pattern at 384cm from double-slit. The pattern was not changed as seen in Fig (04). Fig (04) Then thin Al sheets (3cmx60cm) were set up along the corresponding zero probability positions of the wire grids as illustrated in fig (05) AI sheets ~ Fig (05) Classically photons pass through the space between the sheets but the pattern was not changed and was same as in Fig (02) as can be seen in Fig.(06). Fig (06)
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