ساينس الصف الثالث الاعدادي – الفصل الدراسي الاول ساينس تالتة اعدادي – ترم اول In This part we will study : Lens It is a transparent medium that refracts the light and is limited with two spherical surfaces and is usually made of glass or plastic Uses of lenses: 1 – in medical eye glasses ((for reading or walking)) 2 – in fixing watches. 3 – In war they use binoculars to follow the battle. 4 – used in manufacture of many things like Projector, cameras and magnifying lenses. The types of lenses 1 Convex lens (converging) Concave lens (diverging) Study the previous figure and identify the following concepts: The focus of the convex lens (converging): If the sun ray or any light from any distant source fall on the lens we notice that ray passing through the lens is collected in one point called “the focus of the lens”. Conclusion 1 – convex lens is a converging les collect refracted rays. 2 – th point of collection rays is called ” the focus of the lens (F)” 3 – the distance between the focus of he lens and its optical center is called ” focal length (f) 4 – (f) = 1/2 ( r ) radius of curvature. لمتابعة مستر احمد الباشا وكل ما يخص الساينس : جروب الفيس بوك http://bit.ly/2Of1mcN صفحة الفيس بوك http://bit.ly/2Gq5xMo بالتوفيق مستر احمد الباشا