Question

Q 15: A camera with a 7.0-cm focal length lens is used to photograph a person who is 2.0 m tall. The height of the image on the film must be no greater than 7.0 cm. Calculate the closest distance the person can stand to the lens.

Q 19: A man who can produce sharp images on his retina only of objects that lie from 55 cm to 290 cm from his eyes needs bifocal lenses. Determine the desired focal length of the upper half of the glasses used to see distant objects.

Answer 1

Question 15 magnification = m = = 80 goo 7do di = -1 100 For a lens do-ho- - Low - Fdo OR I 200 + 40 = 1 / 1 -goo + tro 5 - 193 = or do = -193cm 7do do = distance of Person infront of the lens - from the lens - 193 cm Question 19 Far Point at man = 290 cm so the object at infinity should produce image at di = - 290 cm from the lens di do - 17 -290 Loo I = fa -290 em = -2.90 m f = [-2.90 m