CHAPTER 2 LIGHT, SHADOW AND REFLECTION
Light helps us see things. Without light, we won’t be able to see anything.
It is interesting to note that light travels in a straight line.
Luminous objects: Objects which emit their own light are called luminous objects. E.g.: Sun
TYPES OF OBJECTS
If you can clearly see through an object, it is called a transparent object. These objects allow light to pass through them. E.g.: Glass, pure water
If you can’t see through an object at all, it is called an opaque object. These objects do not allow light to pass through them. E.g.: Wood, metal.
If you can see through an object but not very clearly, it is called a translucent object. E.g.: Tracing paper.
When the path of light is blocked by an opaque object, a shadow is formed.
A screen is required to see a shadow.
The shadow of an object depends on how the object is placed against the light.
A PINHOLE CAMERA
To make a pinhole camera, you need two boxes such that one can slide into the other without any gap between them. One side of each box is to be cut open.
Make a small hole in the middle of the opposite face of the larger box.
In the smaller box, a square with a side of about 5 to 6 cm is to be cut from the middle. Cover this box with tracing paper.
Making sure that the side with the tracing paper is inside; slide the smaller box inside the large box.
You can now use this pinhole camera to look at some distant objects.
ECLIPSE: Solar & Lunar Eclipse
When the moon comes between the Earth and the Sun, thereby blocking the light of the Sun, it is called a Solar Eclipse.
When the Earth comes between the Sun and the Moon, it is called Lunar Eclipse.
MIRROR AND REFLECTION
A mirror is a glass plate, one side of which is silvered. We can see our reflection in a mirror.
Reflection is nothing but an image of an object seen in a mirror.