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Volume2, Issue4


EDITORIAL

Page 88PDF: Editorial

S. B. Lisesivdin


ARTICLES

Page 90PDF: Developing Parallel Port I/O Cards For Conducting Simple Physics Experiments

A. Dwivedi, S. Gambhir, P. Arun

Abstract: It is always a fascination to have a computer to collect observations of an routine physics experiment. However, buying interfacing cards not only hurts the pocket but also takes away the pleasure of learning how it is done. This article discusses a simple interfacing project with the 8085-microprocessor kits that are available in under graduate college labs followed by using the knowledge gained to interface the developed card to a computer’s parallel port. Demonstrating how to study the IV characteristics of a p-n diode with this interface card emphasizes the utility it can have in a physics lab. Also, since the whole project was done within Rs (Indian) 1000/- it can easily be popularized.


Page 99PDF: Role of high-speed solar wind streams on cosmic ray nucleonic intensity and solar/interplanetary/geomagnetic parameters during low amplitude days

R. Agarwal, R. K. Mishra

Abstract: There are two types of high-speed solar wind streams classified in two categories: coronal hole associated and flare generated streams. These two types of streams are classified in two categories based on magnetic field and solar wind plasma parameters. In the present work we have studied the characteristic of cosmic ray nucleonic intensity along with solar/geomagnetic parameters and their inter correlation on the onset of high-speed solar wind streams during low amplitude days. The two types of solar wind streams (corotating streams and flare-generated streams) produced significant deviations in cosmic ray intensity and other solar/ geomagnetic parameters during low amplitude anisotropic wave train events. The cosmic ray intensity tends to decrease, whereas the solar wind velocity tends to increase after the on set of corotating stream. Both the geomagnetic activity index (Ap) and disturbance storm time index (Dst) decreases sharply from one day prior to one day after the arrival of corotating stream. Both of these are also found to depressed significantly five days after the arrival of corotating stream. Both the cosmic ray intensity as well solar wind velocity are found to decrease prior to the arrival of flare generated stream and increase after the arrival of stream with a time lag of 1 or 2 days. The solar activity (represented by sunspot numbers) increases sharply prior to the arrival of flare-generated stream up to day +3 with a significant depression on the onset of stream. It is noteworthy that both Ap and Dst index significantly depressed on the arrival of flare-generated stream, whereas both of these are found to increase prior to the arrival of stream.


Page 108PDF: Magnetic properties of diluted magnetic semi conductors and Cd0.5Mn0.5Te nanoparticle

R. Masrour, M. Hamedoun, A. Hourmatallah, K. Bouslykhane, N. Benzakours

Abstract: The magnetic properties of diluted magnetic semi conductors (DMS) are investigated. We have evaluated the critical temperature from the nearest neighbour interactions and the energy exchange for the different diameter of the nanoparticle by using the mean field theory. The shifts of the critical temperatures from the bulk value can be described by a power law, where is the inverse of the correlation length exponent. The obtained value is . The magnetic phase diagrams have been determined by the High-temperature series expansions. A spin glass state has been obtained for x


LETTERS

Page L10PDF: Motion of photons in time dependent spherical gravitational fields

E. N. Chifu, S. X. K. Howusu, A. Usman

Abstract: Schwarzschild’s metric is extended to obtain a generalized metric for the gravitational field exterior to time varying spherical distributions of mass. The general relativistic equation of motion for a photon in the gravitational field of a time varying spherical distribution of mass is derived .The second-order differential equation obtained is a modification of the equation of motion in Schwarzschild’s field. It introduces a unique dependence of the motion of a photon in this field on Newton’s scalar potential exterior to time varying spherical bodies.