light

• Light travels in a straight line.
• A line draw perpendicular to the plane of the mirror at the point of incidence of light is called normal
• The angle between incident ray, reflected ray and normal is always equal (angle of incidence = angle of reflection)
• The angle between the incident ray and the normal is called the angle of incidence
• The angle between the reflected ray and the normal is called the angle of reflection
• Angle of incidence = Angle of Reflection
• laws of reflection

  • The incident ray , the reflected ray and the normal, all lie on the same plane
  • the angle of incidence is equal to the angle of reflection
• The reflected light rays parallel to one another will be reflected only in one direction , this is know as regular reflection
• light falling on irregular or rough surface will reflect in different directions , this is called diffused reflections
• The phenomenon in which the image of an object appears to have left-right inversion is called lateral inversion.
• Images formed by a plane mirror are always virtual and upright
• Images formed by a plane mirror undergo lateral inversion
• The size of the image formed by a plane mirror is the same as that of the object
• The distance of the object from the mirror is equal to the distance of the image from the mirror
• when two or more mirrors are places together light undergoes reflection multiple times from the different mirror and we can see many images , this is called multiple reflection of light
• A periscope is used to see objects situated at higher level
• Kaleidoscope is used by fabric designers to create beautiful patterns
• Refraction is the phenomenon in which a light ray passing obliquely from one medium to another medium of different density, chsnges the direction of its path.
• air is optically a rarer medium
• water is optically a denser medium
• isaac newton discovered that sunlight is composed of different colours of light
• This process of splitting of white light into its constituent colours is called dispersion of light.
• The band of colours obtained on the screen due to the splitting of white light is called spectrum
• The human eye is a slightly asymmetrical sphere of nearly 2.5cm diameter.