light (science)

• light is a form of energy
• light only moves in a straight line
• the phenomena of light moving in a straight line is known as rectilinear propagation of light
• The change in the direction of light after falling on a surface is called reflection of light.
• The bouncing of light on striking a given surface is called reflection
• there are 2 types of reflection
• diffused reflection and regular reflection are the 2 types of reflections
• when light is reflected in such a manner that the reflected rays are also parallel to each other. When these parallel reflected rays are received by the eye, they produce a glare. This is known as regular reflection.
• When a parallel beam of light falls on a rough surface, the reflected rays are scattered in different directions. This is known as diffused reflection. It is the diffused reflection that enables us to see objects without a glare.
• Diffused reflection occurs from surfaces which are rough and have many irregularities in them.
• The path traced by a beam of light is known as a ray
• the incident ray It is the ray of light incident on the reflecting surface
• the point on the surface where the incident ray strikes is known as the point of incidence
• the ray of light bounces off and moves away from the surface. This ray of light reflected from the surface after reflection is called the reflected ray.
• the normal is an imaginary straight line at the point of incidence drawn perpendicular to the surface.
• the angle of incidence It is the angle between the normal and the incident ray.
• the angle of reflection is the ange between the normal and the reflected ray.
• The 2 laws of reflection

  the angle of incidence is equal to the angle of reflection.

  The incident ray, the normal, and the reflected ray all lie in the same plane.
• A plane mirror is a smooth, polished surface that acts as a reflecting surface.
• The copy of the object in the mirror is called its image.
• when the right appears as the left and left appears as the right it is known as lateral inversion
• periscopes, kaleidoscopes, looking glasses and box-type solar cookers. are uses of a plane mirror
• a mirror with curved surfaces is called a spherical mirror
• The inner side of a spoon is the concave side
• The outer side of a spoon is known as the convex side
• the image of an object that can be obtained on a screen is known as the real imaage
• image that cannot be touched or obtained on a screen is known as the virtual image
• a concave mirror is Virtual when the object is very close to the mirror Real in all other cases
• a concave mirror Depending on the position of the object from the mirror, the image could be diminished, enlarged, or of the same size as the object
• a concave mirror is Erect when virtual, Inverted when real
• a convex mirror is virtual
• a concave mirror is always diminished
• A convex mirror is always erect
• uses of concave mirrors are

  1. Used by dentists to obtain a large virtual image of the teeth
  2. Used in headlights of cars/torches
  3. Used as makeup and shaving mirrors
  4. Used in concentrator type solar cookers
  5. Used in reflector type telescopes
• uses of convex mirror is

  1. Used in vehicles as rear view mirrors as they can form the images of objects spread over a large area
  2. Used in shops/malls for surveillance
• A convex mirror is

  1. Used in vehicles as rear view mirrors as they can form the images of objects spread over a large area
  2. Used in shops/malls for surveillance
• A lens which is thicker in the middle and thinner at the edges is called a convex lens
• a lens which is thinner in the middle and thicker at the edges is a concave lens.
• convex lens is a converging lens.
• the point where the rays of light meet is called the focal point