REFLECTION

• Reflection is the bouncing back of light into the same medium it has been traveling after striking a surface.
• The ray that strikes the surface is called the incident ray.
• The ray that rebounds from the surface is called reflected ray.
• A line perpendicular to the surface at the point of incidence is called the normal
• The point of incidence is the point at which light strikes the surface
• The angle between the incident ray and the normal ray is called the angle of incidence.
• The angle between the reflected ray and the normal is called the angle of reflection.
• Two types of reflection:

  • Regular or Specular Reflection
  • Diffuse Reflection
• The Angle of Incidence is equal to the Angle of Reflection.
• When a group of parallel rays strikes a smooth flat surface, such as a mirror, the reflected rays are parallel to one another.
• Regular reflection is when a group of parallel rays strikes a smooth flat surface, and then the reflected rays are parallel to each other.
• Diffuse Reflection - When a group of rays strikes a rough surface, the normal point of incidence is different for each ray.
• Diffuse reflection is more common than regular reflection
• Specular or Regular reflection is an important principle in a reflecting telescope.
• You would not be able to see your image without regular reflection.
• A ray of incidence on a surface is 33 degrees from the normal. Whats the angle of reflection?

  33 degrees
• A ray of incidence on a surface is 33 degrees from the normal. What is the angle between the incident ray and the reflected ray?

  66 degrees
• A mirror is any surface that is smooth enough to produce a regular reflection of light incident upon it.
• Two types of Mirrors:

  • Plane Mirror
  • Spherical Mirror
• Plane mirror - Mirror with a flat surface.
• The ordinary mirror you have at home is an example of a Plane Mirror
• Spherical Mirrors - Has a reflecting surface taken from the surface of a sphere.
• Spherical mirrors may be:

  • Concave
  • Convex
• Concave Mirrors - Curves inward in the direction of the incident rays.
• Convex Mirror buldges outward to the incident rays.
• Real image - Is formed by the actual intersection of reflected rays.
• Real image is formed in front of the mirror and is always upside down relative to the object.
• Real images can be projected on a screen placed in front of the mirror.
• Virtual image is always formed behind the mirror and is always upright relative to the object.
• The virtual image cannot be projected onto a screen because it does not exist as an actual image.
• Magnification is the size of the image relative to the size of the object.
• A magnification of 1 means that the image and the object are of the same size.
• A magnification of less than 1 means that the image is smaller than the object.
• A magnification of greater than 1 means that the immage is bigger than the object.
• Images formed by plane mirrors are always virtual, upright, the same size asa te object. Hence, magnification equal to 1.
• Laterally reversed means that the left of the object becomes the right of the image, and vice versa.
• A ray diagram is useful in locating and characterizing the image formed by a mirror.
• Broken lines are usually used to denote the extension of light rays and a virtual image.