Reflection of Light by Spherical Mirrors | Class 10 Physics | NCERT Explained | Cyton Academy скачать в хорошем качестве

Reflection of Light by Spherical Mirrors | Class 10 Physics | NCERT Explained | Cyton Academy

A spherical mirror is a mirror whose reflecting surface forms a part of a hollow sphere. Depending on which side of the sphere is polished and reflective, we get two types of spherical mirrors. Concave The inner (cave-like) surface is reflective. The mirror curves inward, like the inside of a bowl. Convex The outer surface is reflective. The mirror curves outward, like the back of a spoon. Key Terms & Definitions Centre of Curvature (C) The centre of the full sphere of which the mirror is a part. All radii of the sphere meet at this point. It lies in front of a concave mirror and behind a convex mirror. Radius of Curvature (R) The distance from the pole of the mirror to the centre of curvature. It is the radius of the sphere from which the mirror is cut. Principal Axis The straight line passing through the centre of curvature and the pole of the mirror. It is the axis of symmetry of the mirror. Pole (P) The midpoint of the reflecting surface of the mirror. It is the geometric centre of the mirror's curved surface. Principal Focus (F) The point on the principal axis where all rays parallel to the principal axis meet (or appear to meet) after reflection. • Concave: For a concave mirror: the focus is in front of the mirror — it is a real focus. • Convex: For a convex mirror: the focus is behind the mirror — it is a virtual focus. Focal Length (f) The distance between the pole (P) and the principal focus (F). The focal length is always half the radius of curvature: f = R / 2 Aperture The diameter of the circular boundary of the mirror's reflecting surface. The aperture determines how much light the mirror can collect. Concave Mirror — Convergence of Light A concave mirror converges (brings together) the parallel rays of light that fall on it. This is why it is also called a converging mirror. Convex Mirror — Divergence of Light A convex mirror diverges (spreads out) the parallel rays of light that fall on it. This is why it is also called a diverging mirror. Rules of Reflection for Spherical Mirrors • Rule 1 (Parallel ray): Use when ray comes in parallel — it reflects through F (concave) or away from F (convex). • Rule 2 (Through C): Use when ray goes through C — it reflects straight back through C. • Rule 3 (Through F): Use when ray passes through F — it reflects parallel to principal axis. • Rule 4 (At pole obliquely): Use when ray hits the pole — it reflects at equal angle on the other side of the axis