QUIZ 25(TEST 4) AND (TEST 3)

7, 11, 12, 13, 14, 21, 22, 23, 24, 31, 32, 48, 51, 52
TURN IN: 7, 11, 12, 13, 14, 22, 23, 32, 48,  52
7.  Remember f is adjusted to keep di = constant. 1/di  + 1/do = 1/f.  Note:  do = 58 m is given. You need di to get f. But m =  - 0.024 / 28 = - 0.008571 = -di/do.   Find  di then find f. 
11. Check back later
12. This is just like example 25-5 except that the eye-lens distance is not negligible. In that case you write 
1/f = 1/do + 1/di, where do = 55 cm - 1.8 cm. You want di = -(115 - 1.8) cm.  Find f. 
13. See example 25-6 (a), which calculates the problem with a far  point of 17 cm. You want to find f in order for distance objects (d0 = infinity)  to be focused at the given far point, in this case 14 cm instead of 17 cm. So 1/f = 1/do + 1/di, where do = infinity and di = -(0.14 - 0.020) m, correcting for the 2.0 cm = 0.020 m eye-lens distance. Find f.  

Re-do the problem neglecting the eye-contact lens distance,  taking a cue from example 25-6 (a). . 
14. Another farsighted person ! Again, we'll be using a converging lens to correct the vision by effectively decreasing f. Remember, the eyes lens f could to reaches sufficiently low value for the image to fall on the retina; thus with a correction, the image focused behind retina. 

  We want the final image to be 0.45 m from the eye. We will add a converging lens 2.0 cm from the eye, making  the image distance di = -0.43 m.   We assume do = 0.23 m, correcting for the eye lens distance.   Solve for f. Is f > 0? If not you made a mistake.  See example 25-5. 
22. M = (ho/do)/(ho/N) = N/do.  If the eye is relaxed the image distance di = -infinity, which means that do = f, so M = N/f. 
23. (a) M = N/do   = N*(1/f - 1/di) =  N*(1/f + 1/N) = N/f  +  1 Find f. (b) M = N/f. Find f. 
32. Use equation 25-3. Convert D (Diopters) to meters. See page 648. 
48. Use equation 25-7 and example 25-10. 
52. 

(a) Use equation 25-7 in this sense: theta = s/r = 1.22*lambda/D, where s is the distance between the two headlights s, r is the distance from the eyes to the headlights , and D is the pupil diameter .    The wavelength is given. Find r.

(b) Use equation 25-7.