Reflection of light

• Plane (flat) mirrors produce a reflection.
• Rays from an object reflect off the mirror into our eyes, but we see them behind the mirror.
• • The mirror image has these properties:
  • Image is the same size as the object
  • Image is the same distance from the mirror as object
  • A line joining corresponding points of the image and object meet the mirror at a right angle
  • Image is virtual: no rays actually pass through the image and the image cannot be formed on a screen

  
• Laws of reflection:

  • Angle of incidence = angle of reflection
  • The incident ray, reflected ray and normal are always on the same plane (side of mirror)
• Critical angle: an angle at which the i = 90 degrees, where the reflected ray bends at a 90 degree angle
• If the angle of incidence is greater than the critical angle there is no refracted ray, there is total internal reflection.
• If the angle of incidence is less than the critical angle the incidence ray will split into a refracted ray and a weaker reflected ray.

  
• Formula for the refractive index is: $\frac{Speed\ of\ light\ in\ vacuum}{Speed\ of\ light\ in\ a\ medium}\ =$$\ \frac{\sin\ i}{\sin\ r}$
• Critical angle: $\sin^{-1}\frac{1}{n}$