Proceedings of the Technical Session of Institute of Physics, Sri Lanka 2 (1986) c1

Optical Investigation of the Electrodeposited Cuprous Oxide Film Electrodes using Photocurrent Spectroscopy
W. Siripala
Department of Physics, University of Kelaniya, Kelaniya

Thermally grown Cuprous Oxide has known as a p-type semiconductor and the p-type conductivity is attributed to the Copperion vacancies created in the crystal lattice during the oxide formation. However, we have observed, for the first time, that the cathodically deposited Cu₂O films on various metal substrates produce n-type photoconductivity. Photoelectrodes were used in a photoelectrochemical call containing an aqueous electrolyte. Photocurrent-potential behaviour demonstrate that the photoresponse is anodic and the analysis of the spectral response measurements reveal thet Cu₂O has a direct bandgap of 2.0 eV. Tenactive assignment of Oxygen ion vacancies in the electrodposited cupprous Oxide films, which would result in n-Cu₂O, is proposed.

Proceedings of the Technical Session of Institute of Physics, Sri Lanka 2 (1986) c2

Preliminary Studies of the Earth's Fair Weather Electric Field in Sri Lanka
K.P.S.C. Jayaratne and A.S. Dissanayake
Department of Physics, University of Colombo

A large number of instruments of field mill type have been developed in the past, for the measurement of electric fields both in the atmosphere and in the laboratory. A recently developed, highly reliable measuring instrument called "Dual Channel Wide Band Field Mill" is used for continuous and accurate measurements of earth's vertical potential gradient under fair weather and thunderstorm conditions.

In Colombo, diurnal variation of the potential gradient has double oscillation type variation of the months of August, September and October. During daytime the potential gradient has a higher value than at night time. The calculated height of the AEEL (Atmospheric Electric Equalisation Layer) over Sri Lanka is 67 Km.

Proceedings of the Technical Session of Institute of Physics, Sri Lanka 2 (1986) c3

Radioactive Technique for the Measurement of Wave Activity on Sea Shore
K.G. Dharmawardane¹, P.R.D. Rajapakshe² and K.P.S.C. Jayaratne^2
1 Radioisotope Centre, University of Colombo
² Department of Physics, University of Colombo, Sri Lanka

Thorium is a mineral present in Monazite sand in our beaches which contains 1-9 percent of ²³²Th in the from of phosphate with a variable percentage of Thoria (Tho2). An attempt has been made to measure the wave activity on seashore using the radiation of this mineral. Two alternative methods were also used in order to justify the Radioactive Technique. High correlation coefficients were obtained between the two alternative methods and radioactivity technique, implying that the Radioactivity technique could be used effectively to measure the wave activity. The advantage of measuring wave activity by the Radioactivity technique is that it is easier and more convenient than conventional methods. During the course of this research work it seemed possible to develop a radioactive technique to study wave breaking. Further investigations are underway.

Institute of Physics, Sri Lanka