Light

• A ray of light is a path along which light energy travels
• Laws of reflection are obeyed if the

  angle of incidence,I is equal to the angle of reflection, r. The incident ray,the reflected ray and the normal lie on the same plane .
• The normal line is a virtual line which is perpendicular to the reflecting surface at the pt of incidence.
• The angle of incidence, I,is defined as the angle found between the incident ray and the normal.
• The angle of reflection, r, is defined as the angle found between the reflected ray and the normal line.
• The point of incidence is the point on the reflecting surface where light

  ray strikes.
• The incident ray is a light ray hitting the reflected surface.
• The reflected ray is a light ray reflected from the reflecting surface.
• Compression is the region where the particles are close together and has high pressure.
• Rarefraction is the region where the particles are further apart and has low pressure.
• Characteristics of image formed by a plane mirror :

  The image size =object size

  The image distance=The object distance

  The image is upright

  The image is virtual

  The image is laterally inverted.
• Refraction is the bending of light when it is passing from one optical medium to another.
• The law of refraction

  The incident ray, the normal line and the reflected ray all lie on the plane at the point of incidence.
• Characteristics of regular reflection:

  Parallel light rays incident on the surface are reflected in one direction only.

  For such surfaces, the normals at all points of incidence are parallel .
• Characteristics of irregular reflection:

  Parallel light rays incident on the surface are reflected in all directions.

  For such surfaces, the normals at all points of Incidence are not parallel .