When a luminous object AB, such as a lighted candle, is placed in front of the pin hole, an inverted picture A’ B’ of the candle is obtained on the tracing paper. This picture A’ B’ is called the image. The image obtained is upside down (i. e. inverted). The reason is that the light travels in a straight line path. Hence light from the upper point A of the candle passes through the pin hole and strikes
the tracing paper at A’. Similarly, light from the lower point B of the candle passes through the pin hole and strikes the tracing paper (or screen) at B’. Light from all the other points between A and B, on passing through the pin hole strikes the tracing paper in between A’ and B’. As a result, an inverted image of the candle is seen on the tracing paper Fig shows the simple ray diagram for die formation of image.
Ray diagram for formation of image in a pinhole camera.
