Question

(a)What is Pinhole Camera? Draw a neat and labelled diagram to show the formation of image of a lighted candle by it.

(b) Explain the formation of image of a luminous object in a pinhole camera.

Answer 1

(a) The pin hole camera is a simple application of the rectilinear propagation of light.

(b) 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.