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## Activity 16.1 **Aim:** To show rectilinear propagation of light **Materials required:** A long straw of length of about 10 inches, a lit candle **Method:** Hold the straw straight by pointing one end to the source of light. Put your eye at the other hole of the straw. What do you see? Now, ben...

## Activity 16.1 **Aim:** To show rectilinear propagation of light **Materials required:** A long straw of length of about 10 inches, a lit candle **Method:** Hold the straw straight by pointing one end to the source of light. Put your eye at the other hole of the straw. What do you see? Now, bend the straw and look through the hole. Can you see the light? **Observation and Conclusion:** We can clearly see the flame (source of light) through the straight straw. However, when the straw is bent, the flame, or the source of light is no longer visible. This experiment clearly shows that light travels in a straight line. ## Activity 16.2 **Aim:** To create shadows of different shapes (circle and rectangle) using the same object **Materials required:** Light source (flashlight) and a cylinder-shaped object **Method:** When you switch on a torch in a dark room, you will see a straight beam of light. Now, 1. Place a cylinder in front of the light beam horizontally over the ground, blocking the path of the light. What do you see? 2. Place the same cylinder in front of light beam vertically, blocking the path of the light. What do you see? **Observation:** 1. A circular shadow forms on the wall. 2. A rectangular shadow forms on the wall. **Conclusion:** The shadow's outline, also known as a silhouette, have the same shape as the outline of the object blocking the light. 1. A circular shadow is created when the object blocking the light is circular. 2. A rectangular shadow is created when the object blocking the light is rectangular.