What is Shadow?

 What is Shadow?

What is Shadow? When you place an object between your eyes and a source of light will be able to see the light source. The answer is NO. This means that there is a region behind an object where light from the source cannot reach and that particular region will appear dark. This dark region is what we call the object’s shadow. We have learned that the light travels in straight lines. When light reaches an object, it can travel through the object if the object is transparent but light can be absorbed if the object is opaque. Shadows are produced when light hits an opaque object which prevents the light beams from passing through. When an object blocks the light’s path, then darkness appears on the other side. This darkness is called a shadow. Let us take an example where the sun is a source of light. As the earth rotates each day, the sun appears to change position in the sky and changing angles of sunlight affect the appearance of shadows. For instance, on a sunny day, take a potted plant in the ground and watch its shadow move and change shape. When the sun gets low in the sky, the potted plant’s shadow gets longer. Let us perform a simple experiment to note that the shape and size of the shadow produced are determined by distance between an object and its light source. (1) Suspend a ball from the ceiling with the help of a strong thread. (2) Light a torch and hold it at some distance from the ball. (3) Ball being an opaque object blocks the path of light from the torch and shadow is formed on the wall. (4) Observe the size of the shadow. Lets us observe the various instances: (a) If the distance of the object (Ball) from the source (Torch) is decreased, then the size of the shadow increases. (b) If the object (Ball) is moved away from the source (Torch), then the size of its shadow decreases. (c) If the distance between the object (Ball) and the wall is constant, and if the light source (Torch) is moved towards the object, then the size of its shadow increases. Conclusion: The size and shape of the shadow of an object depends on the orientation of the object with respect to the beam of light. The shadow changes in size and shape when the object is placed in a different way in the path of light.