Light, Shadow and Reflection notes for science class 6 NCERT, PSTET and CTET

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 Light, Shadow and Reflection

What are Luminous and Nonluminous objects?

Objects that give out or emit light of their own are called luminous objects. Example: Sun, Torch, Moon, Bulb etc.

Objects which do not give out or emit light of their own are called Nonluminous objects. Example: Table, chair, pen etc.

TRANSPARENT, OPAQUE AND TRANSLUCENT OBJECTS

Transparent: Objects that allow light to pass through it and you are able to see clearly through an object.

Opaque: Objects that allow light to pass through it and you are not able to see through an object.

Translucent: There are some objects through which we can see, but not very clearly. Such objects are known as translucent. Like paper.

SHADOW

  • The dark patch formed by an opaque object on a surface is called as shadow.

Why Shadow formed?

  • When an opaque-objects obstruct light, a shadow forms.
  • We need a source of light and an opaque object, to see a shadow.
  • Shadows give us some information about shapes of object but the information is not always accurate.
  • Shadow do not form clear images.
  • The shadow can be seen only on a screen like ground, walls of a room etc.
  • The shadows do not look different in colour.
  • Images are very different from shadows.

The Pinhole Camera

A pinhole camera is a simple device that captures images without a lens. It operates on the principle of light travelling in straight lines.

Image formed by Pinhole Camera is INVERTED.

Light passing through a pinhole camera's tiny hole projects an upside-down and smaller image on the screen. Rays coming from the image intersect at the pinhole and continue to travel in a straight line.

Changing the distance of the object from the pinhole will also change the size of the image.

#NOTE: Light travels along a straight line, any opaque objects obstruct it,

Reflection

When light rays encounter an object, they can be reflected. The bouncing back of light when it falls on a mirror is called reflection. Mirror reflection gives us clear images. Mirrors work on the principle of reflection, where light bounces off surfaces.



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