Rainbow 🌈 mindmap- light and shadow

0

      Light is a form of energy that affects the eye to produce the sensation of vision.
Two types of sources of light are:
         (1) Natural sources such as sun, stars.             and jugnu.
        (2) Artificial sources such as fire,          electric lamp, electric tube light, a burning. candle, a kerosene lamps heated bodies, etc.

Bodies- as luminous bodies and non  luminous bodies
 Bodies which themselves emit light are called luminous bodies. Examples: torch, electric lamps electric tube light, burning candle, kerosene lamp, sun, stars. Jugnu etc.
 Bodies which do not emit light by their own,   are called non-luminous bodies. Examples: moon, earth, table, book, chair etc.
As medium- transparent , translucent and opaque
A Medium which allows the passage of light through it easily, is called a transparent medium. Examples: glass, air, water etc.
A medium which allows only a small amount of light to pass through it, is called a translucent medium. Examples: butter paper, tracing paper etc.
A medium which does not allow any light to pass tough it, is called an opaque medium. Examples: wood, metals etc. 

Rectilinear propagation of Light -Light travels in a straight line path. 

A simple application of Rectilinear propagation of Light- Pin hole camera .The image formed in a pin hole camera is inverted .

  The shadow of an opaque object is the dark patch obtained on the screen when that opaque object is placed in the path of light.
  • Shadow is formed because light travels in a straight line path.
  • The shadow is similar to the shape of the object.
  • The part of the shadow where no light reaches from the source is completely dark and is called the umbra.
  • The part of the shadow where light reaches from only a portion of the source is partially dark and is called the penumbra

  • .Cases-
  •    By point source

  • There is only umbra in the shadow of an opaque object due to a point source. The umbra is bigger in size than that of the object.
  •      The umbra increases in size if the.      screen is moved away from the object.

  • By  Extended source smaller than object-

  • The shadow of an object due to a light source smaller than the object contains an umbra surrounded by a penumbra. The umbra is bigger in size than that of the object. Both the umbra and penumbra increase in size as the screen is moved away from the source.

  • By Extended source bigger than object -

  • The shadow of an opaque object due to a light source bigger than the object contains an umbra (which is much smaller in size than the object) surrounded by a penumbra. The umbra diminishes while the penumbra increases in size if the screen is moved away from the object.

  • Lunar and solar eclipses are the examples of formation of shadows in nature.
  • A lunar eclipse 

  • is caused on a certain full moon night when the earth comes in between the sun and the moon so that the earth casts its shadow on the moon.
  • A solar eclipse


  •  is caused on a certain new moon’s day when the moon comes in between the sun and the earth so that the moon casts its shadow
Go to following posts to check your knowledge 


Post a Comment

0Comments
Post a Comment (0)
To Top