Spherical Mirrors

Key Notes:

Definition:

Spherical Mirrors: Mirrors with a reflecting surface that forms part of a sphere. They are of two types:

  • Concave Mirror: Inner surface is reflective.
  • Convex Mirror: Outer surface is reflective.

Important Terms:

  • Pole (P): The center of the mirror’s surface.
  • Center of Curvature (C): The center of the sphere of which the mirror is a part.
  • Radius of Curvature (R): The distance between the pole and the center of curvature.
  • Principal Axis: A straight line passing through the pole and center of curvature.
  • Focus (F): The point where parallel rays of light converge (concave) or appear to diverge (convex) after reflection.
  • Focal Length (f): The distance between the pole and the focus. f = R/2ā€‹.

Mirror Formula:

1f = 1/vāˆ’1/uā€‹

  • f: Focal length
  • u: Object distance
  • v: Image distance

Magnification:

m = āˆ’v / u

  • m: Magnification
  • v: Image distance
  • u: Object distance

Laws of Reflection:

  • Angle of incidence = Angle of reflection.
  • Incident ray, reflected ray, and normal all lie in the same plane.

Image Formation by Spherical Mirrors:

  • Concave Mirror:
    • Can produce real or virtual, upright or inverted images depending on the object position.
    • Used in devices like telescopes, headlights, and shaving mirrors.
  • Convex Mirror:
    • Always produces virtual, upright, and diminished images.
    • Used as rear-view mirrors in vehicles.

Ray Diagrams:

  • Concave Mirror:
    • Key rays: Parallel to principal axis, through the focus, and through the center of curvature.
  • Convex Mirror:
    • Key rays: Parallel to principal axis and appear to diverge from the focus.

Let’s practice!