Question

15. A camera lens focuses light from a flower 8 cm in diameter and 30 cm from the lens or to a focal plane 6 cm behind the lens. There, a charge-coupled device (CCD) builds up charge in individual squares (pixels) of the CCD in proportion to the light received. The camera elec- tronics read the charges to form an image. a) What is the focal length of the lens? b) Is the image on the CCD erect or inverted? c) What will be the diameter of the image on the CCD array?

Answer 1

(a) consider focus points center of flower so, neight of flower h_0 = 4 cm u = 30 cm v = 6 cm ea 1/ f = 1/4 + 1/u = 1/30 + 1/6 1/f = 6/30 f = 5 cm (b) m = -v/ u = -6/30 = -1/5 since m is negative image is inverted (c) m = -1/5 = mol/h_0 double rightarrow h_i = -4/5 cm so diameter of on ccD = u/5 times 2 = 1.6 cm