How do we see luminous objects

Encourage students to explain their answer. It is also common for some students to believe that to see an object light must come directly from a luminous source ray B to their eye while simultaneously light must strike the object we see directly ray A as in the diagram below.

Variations of this idea are shown in the probe in diagrams C and D of the multiple choice question above. Students should be invited to test their ideas to determine if ray B in is really required to see the beetle. One way they can do this is to insert an obscuring screen between the source of light and their eyes to eliminate ray B. The diagrams C and D in the probe would assist with investigating this understanding further.

This activity is designed to demonstrate that non-luminous objects do reflect light. It can also be used to provide further insights into the nature of coloured surfaces.

It will challenge the notion that non-luminous objects do not reflect light. Have students construct a white page with multi coloured paper squares glued along one side as shown here.

Students should then place the constructed page against another white page at an acute angle and view the coloured light reflecting off the second white page above the coloured squares as shown. Ask students to explain using a ray diagram the path of the reflected light from the coloured squares to their eyes. She was surprised last night when she saw the light from a firefly first-time.

Now, if we observe all the objects closely, we will see a few objects like the sun, emergency light, and firefly produce light. But other objects like the person Rima, book, chair, notebook, pen, etc. Hence, the concept of luminous and non-luminous or illuminated objects comes into the study. Luminous means giving light. Hence, the luminous object means the object which gives light.

The non-luminous or illuminated object means the object which can not give light. The object which produces light is known as a Luminous Object. It has the following characteristics:. There are so many examples of luminous objects in the universe, few of them are listed for reference,. The object which is not able to produce light is known as a Non-Luminous Object or Illuminated objects.

Do you want to know about the examples of transparent objects or translucent objects , check our other article. We know that if the light is present, we can see the object. Remember that, if the light is coming from an object to our eyes, then only we see the object.

Now, in the same philosophy, this object means, here, it produces light that comes directly to our eyes and we can see. Look at the example, we see the bulb. How do we see it? There is nothing present in the region between the laser and the mirror that is capable of reflecting the light of the beam to students' eyes.

But then the phenomenal occurred as it often does in a Physics class. A mister is used to spray water into the air in the region where the light beam is moving. Small suspended droplets of water are capable of reflecting light from the beam to your eye.

It is only due to the presence of the suspended water droplets that the light path from the laser to the mirror could be detected.

When light from the laser a luminous object strikes the suspended water droplets the illuminated object , the light is reflected to students' eyes. The path of the light beam can now be seen. With light, there can be sight. But without light, there would be no sight. None of us generate light in the visible region of the electromagnetic spectrum.

We are not brilliant objects please take no offense like the sun; rather, we are illuminated objects like the moon. We make our presence visibly known by reflecting light to the eyes of those who look our way. It is only by reflection that we, as well as most of the other objects in our physical world, can be seen. We enjoy seeing the scenes of sunrise and sunset.

On the way to the market, we see cars, buses, and people in colorful dresses. After the sunset, all these scenes change. Everything around us appears dark. In a completely dark room, we cannot see any object present in the room. When we switch on an electric bulb or light a candle, the objects present in the room become visible. Without light things cannot be seen Light helps us see objects.