part ment, Fac ulty of Sci ence, Leb a nese Uni ver sity, Bei rut, Leb a non 2 Phys ics De part ment, Fac ulty of Sci ence, Al ex an dria Uni ver sity, Al ex an dria, Egypt 3 De part ment of Phys ics, Fac ulty of Sci ence, Bei rut Arab Uni ver sity, Bei rut, Leb a non Sci en tific pa per