Luminous objects are those which emit out their own light, e.g. sun, stars, tube light, bulb, etc., whereas non-luminous objects are those which shine by reflecting the light of the luminous objects. They do not emit their own light, e.g. moon, book and iron do not shine at all and are opaque objects.

Non-luminous objects are those which shine by reflecting the light of the luminous objects. They do not emit their own light, e.g. moon. So, it is the moon which is non-luminous.

Opaque objects form dark shadows as transparent and translucent objects allow light to pass through them.

Non-luminous objects are those which shine by reflecting the light of the luminous objects. They do not emit their own light, e.g. moon.

Whenever an opaque object is kept in the path of the light, it forms a dark patch behind itself. This dark patch is known as a shadow. It is always black in colour irrespective of the object colour or light colour falling on it.

A shadow is always formed by an opaque object. The shape of a shadow depends upon two factors:

1. Size of the source of light
2. Position of the source of light. Smaller the size of the light source, larger will be the image formed and greater is the distance between the object and the light source, lighter will be the image formed.

So, a metal sheet is opaque in nature.

So, a glass pane is not translucent in nature.

The object which emit or give out their own light are called luminous object e.g. Sun, Stars, torch, electric bulb, tube light etc.

The object do not allow light to pass through them are called opaque objects and nothing can be see through these objects Eg. Table, chair, book, iron (or any metal)

Rubber, wood and metal are the objects which do  not allow light to pass through then at all and nothing can be see through these objects. Whereas glass sheet is a transparent object as it allows light to pass through it.

Air is a transparent mixture of gases which allow light to pass through it whereas soil, rock and wood are the examples of opaque object i.e. they do not allow light to travel through them at all.

Sun, stars and fireflies are the examples of natural sources of light and also the luminous object. Moon is also a natural source of light through it is non-luminous. Electric bulb, torch streetlight and candle are not natural object as they are being industrially prepared but as they emit their own light so are known as artificial source of light.

To see any object we need to have a source of light that allows us to see the objects

Sun, stars and fireflies are the examples of natural sources of light and also are the luminous objects. Moon   is also a natural source of light through it is non-luminous. Electric bulb, torch streetlight and candle are not natural object as they are being industrially prepared but as they emit their own light so are known as artificial source of light. So moon is a natural source of light.

So the objects which allow light to pass partially are called translucent objects.

Sun, stars and fireflies are the examples of natural sources of light and also the luminous object. Moon is also a natural source of light through it is non-luminous. Electric bulb, torch streetlight and candle are not natural object as they are being industrially prepared but as they emit their own light so are known as artificial source of light. So it is the moon which is a natural source of light.

Whenever an opaque object is kept in the path of the light it forms and dark patch behind itself. This dark patch is known as shadow. It is always black in colour irrespective of the object colour or light colour falling on it. As empty cardboard cartons are opaque so they do not allow light to pass through then and always etc as dark room.

Whenever an opaque object is kept in the path of the light it forms a dark patch behind itself. This dark patch is known as shadow. It is always black in colour irrespective of the object colour or light colour falling on it.

Shadow is always black on colour irrespective of the colour of the object. Size and position of shadow depends upon the size and position of source of light. Shadow gives almost the same shape as that of the object; so it is the shape of the object which can be seen on shadow.

Shadow is always formed by an opaque object. Shape of the shadow depends upon 2 factors:

1.         size of source of light
2.         position of source of light. Smaller the size of light source, larger will be the image, formed and greater is the distance between the object and light source, light will be the image formed. A shadow is always black is colour and is different in size than that of the object.

A pinhole camera refers to a device which is used by making a hole in the cardboard (close box) for the entry of light from one point. The other surface side of the camera is having a tracing paper pasted on it      which acts as screen. When light enters through hole after getting striked from an object, then it undergoes internal reflections to create the image of that object on the tracing paper acting as screen.

Whenever an opaque object is kept in the path of the light, it forms a dark patch behind itself. This dark patch is known as a shadow. It is always black in colour irrespective of the object colour or light colour falling on it. So, it is an opaque object and a source of light, required to see the shadow.

So, it is water which is transparent in nature whereas iron, table and cloth are all examples of opaque materials.