Revision Notes on Luminous Objects and Non-Luminous Objects

• Objects that produce their own light are called Luminous Objects. Example, Sun, Fire

• Objects that do not produce their own light but are visible when reflect light falling on them are called Non-Luminous Objects. Example - Table, planets. Non-luminous objects can be classified as-

Shadows are dark regions formed when an opaque object blocks the path of light. This formation is possible only because light only travels in a straight line.

How to make a Pinhole Camera?

Step 1: Take two cardboard boxes one larger than the other such that one box slides into the other without any gap.

Step 2: Cut out open one side of each box. On the opposite side of the larger box cut a small hole in the centre.

Step 3: On the opposite side of the smaller box cut a square of about 5 cm and cover this open area with a tracing paper.

Step 4: Slide the smaller box inside the larger one such that the side with the tracing paper is on the inside.

Step 5: Cover the camera and your head with a black cloth and then get ready to observe the distant objects.

Fig: A Pinhole Cameria

It is a simple camera with a small aperture and forms an inverted image of the object.

Mirrors and Reflections

All of us are used to seeing a mirror every day. The image that we see in a mirror is called Reflection. The mirror deflects the direction of the light that falls upon it.

Fig: A Mirror Changing the direction of light as it falls on it