Page 1 - Lesson Note-Shadow

SAI INTERNATIONAL SCHOOL
Class-6
Lesson Note

Subject-Physics
Ch-Light, Shadow & Reflection
Subtopic- Shadow

Shadow:
The dark patch obtained on the screen by an opaque object when it is placed in the
path of source of light is known as shadow.
Materials required for the formation of shadow:
• An opaque object
• A source of light
• An opaque screen

How shadow is formed?
Light travels in a straight line, that is, it does not bend round the edges of an opaque
object. So, no light could reach behind the object. We, therefore, see a dark patch
behind the object. So the shadow is formed due to the absence of light.

Nature of a shadow:
• It is always black
• Shadow can be divided into two regions- umbra and penumbra.
• Umbra: It is the central and darkest part of the shadow where no light
reaches.
• Penumbra: It is a faint part of a shadow that receives some amount of light.
• Penumbra lies around the umbra.