Chapter 19, Problem 1CQ

To determine

The reason for the circles formed when the light is passed through the gaps in the leaves of irregular shapes.

Answer to Problem 1CQ

Circles of varying brightness are formed because the gaps acts like a pinhole camera and the image formed is inverted image of the object and here object is Sun.

Explanation of Solution

The shape of image on the screen also depends upon the distance of the screen from the point where light is coming. If the distance of the screen from the pinhole camera is varied, the size of image also varied.

If the screen is close to gaps or holes formed by leaves, then the spot of light will have the same shape on the screen as the shape of the hole or gap.

But in this case, screen is the ground which is very far away from the spot of light, therefore the spot acts like a pinhole camera and image size will increase.

Brightness of the image will decrease because light spreads over a larger area. The bright spots varying brightness are observed and are circular in shape because the object is sun and inverted image of the object is obtained on the screen. Spots are not extremely sharp because light gets diffracted through a small hole.

Conclusion:

Thus, Circles of varying brightness are formed because the gaps acts like a pinhole camera and the image formed is inverted image of the object and here object is Sun.