Physics of Mirrors

Mirrors

• Types of Mirrors:

  • Plane Mirrors: Flat mirrors that reflect light, maintaining the image's original size and orientation.
  • Spherical Mirrors: Curved mirrors that can converge or diverge light, used in applications like telescopes and magnifying glasses.
  • Concave Mirrors: Curved inward, used to focus light and form real images.
  • Convex Mirrors: Curved outward, used to diverge light and form virtual images.

• Mirror Equation:

  • 1/f = 1/do + 1/di, where:
    • f: Focal length of the mirror
    • do: Object distance
    • di: Image distance

Refraction

• Definition: The bending of light as it passes from one medium to another with a different optical density.
• Snell's Law:
  • n1 sin(θ1) = n2 sin(θ2), where:
    • n1 and n2: Refractive indices of the two media
    • θ1 and θ2: Angles of incidence and refraction
• Total Internal Reflection: When light hits a surface at a shallow angle, and is completely reflected back into the original medium.
• Critical Angle: The minimum angle of incidence that results in total internal reflection.

Mirrors

• Types of Mirrors: There are four main types of mirrors, each with unique characteristics.
• Plane Mirrors: Reflect light, maintaining the image's original size and orientation, and are flat.
• Spherical Mirrors: Curved mirrors that can converge or diverge light, used in applications like telescopes and magnifying glasses.
• Concave Mirrors: Curved inward, used to focus light and form real images.
• Convex Mirrors: Curved outward, used to diverge light and form virtual images.

Mirror Equation

• 1/f = 1/do + 1/di: The mirror equation relates the focal length of the mirror (f) to the object distance (do) and image distance (di).

Refraction

• Definition: Refraction is the bending of light as it passes from one medium to another with a different optical density.
• Snell's Law: The law states that n1 sin(θ1) = n2 sin(θ2), where n1 and n2 are the refractive indices of the two media, and θ1 and θ2 are the angles of incidence and refraction.
• Total Internal Reflection: When light hits a surface at a shallow angle, it is completely reflected back into the original medium.
• Critical Angle: The minimum angle of incidence that results in total internal reflection.

Reflection of Light

Definition

• Reflection of light occurs when light hits a surface it cannot pass through, changing its direction and bouncing back.

Laws of Reflection

• Incident ray, reflected ray, and normal to the surface all lie in the same plane.
• Angle of incidence (θi) equals angle of reflection (θr).
• Distance of incident ray from normal equals distance of reflected ray from normal.

Types of Reflection

Specular Reflection

• Occurs on smooth surfaces, producing clear and undistorted images.

Diffuse Reflection

• Occurs on rough surfaces, resulting in scattered reflections.

Factors Affecting Reflection

• Surface roughness determines type of reflection (specular or diffuse).
• Angle of incidence affects angle of reflection.
• Surface material affects reflectivity, with different materials reflecting varying amounts of light.

Applications of Reflection

• Mirrors use specular reflection to produce images.
• Optical instruments (telescopes, microscopes) use reflection to redirect light.
• Lighting applications (reflectors, diffusers) utilize reflection.

Important Concepts

• Reflectivity measures the ratio of reflected light to incident light.
• Albedo measures how much light a surface reflects.