تسجيل الدخول

تسجيل

The Formation of Images

المؤلف:  GEORGE A. HOADLEY

المصدر:  ESSENTIALS OF PHYSICS

الجزء والصفحة:  p-438

2025-12-16

366

An image is the picture of an object formed by rays of light coming from it. The image formed by rays passing through a small opening is always inverted. That this must be so is shown by a study of Fig.1, which illustrates the formation of an image by a pinhole camera. Since all the light that forms the image comes through the pinhole, all the rays that are not parallel must cross in passing through it. The ray coming from the top of the object forms its image at the bottom. The ray from the bottom of the object goes to the top of the image. The ray from the right side strikes the left, etc. Hence there is a complete reversal in the image.

If a room is darkened and sunlight is let into it through the side of a Venetian blind, a series of sun images will be formed on the walls or floor wherever the light falls. If sunlight comes through a dusty window pane into a darkened room, the lighted part of the wall opposite is made up of a number of overlapping images of the sun. In partial eclipses of the sun, the light coming through small openings in the leaves of trees will form inverted crescent images of the sun on the ground.