6th Class Science Light, Shadows and Reflections

Light, Shadows and Reflection

Synopsis

• Objects which emit light energy by themselves are called luminous bodies.

          e.g., the sun, the stars, and glow worms.

•  The bodies which do not have light energy of their own but reflect the light energy falling on them and hence are visible to us are called non-luminous bodies.

         e.g., the moon, objects around us, books, chairs, buildings, trees, etc.

• The moon appears bright due to the reflection of sunlight falling on it.

• Transparent bodies are substances through which light is propagated easily,

          e.g., glass/water/etc.

• Translucent bodies are substances through which light is propagated partially.

          e.g., oil, ground glass, etc.

• Opaque bodies are substances through which light is not propagated.

         e.g., wood, iron, etc.

• Light travels in straight lines.

• Smooth surfaces like mirrors form images.

• The shadow of an object is formed because of the rectilinear propagation of light. A shadow is the area of darkness formed on the screen, when an opaque body is placed in between the screen and a source of light

• A pin hole camera uses the principle of rectilinear propagation of light. It produces a real image which is much smaller than the object and is inverted (upside down).

•  The returning of a light ray passing through an optical medium into the same medium from the surface of the second medium is called the reflection of light.

• The surfaces which reflect light are called reflecting surfaces.
•  Images are different from shadows.