ساينس الصف الثالث الاعدادي – الفصل الدراسي الاول ساينس تالتة اعدادي – ترم اول In This part we will study : Some concepts definitions: Center of curvature: center of the sphere that the mirror is considered a part of it. Radius of curvature: radius of the sphere that the mirror is a part of it. Secondary axis The pole of mirror: is the point that is in the middle of the reflecting surface of the mirror. The principal axis: is the straight line passes by the pole of the mirror and its center. The secondary axis: Any straight line that passes by the center of curvature and any other point on surface except the pole of mirror. Focus: The point of collection of the parallel rays after being reflected from concave mirror . Focal length: The distance between the focus of the concave mirror and its pole. 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