The next five questions pertain to the following situation: In the figure are shown two lenses. The focal length fi is unknown, but f-14 cm. The lenses are separated by 25 em. When an object 1 em high is located 5 cm in front of the first lens, it produces an image (not drawn) 10 em to the right of the first lens. f2- 14 cm 5cm 25cm 2. Find fi the focal length of the first lens. (A) (B) (C) fi 3.33 cm fi = +10.0 cm fi--8.33 cm . Find d2 the position the image formed by the second lens, expressed as a distance rom the second lens. (A) (B) (C) d- 130 cm d- 190 em d2 = 210cm Solution 12) from lens forrmula we get 1/v + 1/u = 1/f Here u is object distance, v is image distance and f is focal length Therefore, 1/10 + 1/5 =1/f f=3.33 cm Correct option is a 13)for the second lens, image from first lens is the object Object distance=25-10=15 cm Focal length=14 cm Let image distance be v 1/15 + 1/v = 1/14 v=210 cm Correct option is c .

1. The next five questions pertain to the following situation: In the figure are shown two lenses.
The focal length fi is unknown, but f-14 cm. The lenses are separated by 25 em. When an object
1 em high is located 5 cm in front of the first lens, it produces an image (not drawn) 10 em to the
right of the first lens. f2- 14 cm 5cm 25cm 2. Find fi the focal length of the first lens. (A) (B) (C)
fi 3.33 cm fi = +10.0 cm fi--8.33 cm . Find d2 the position the image formed by the second lens,
expressed as a distance rom the second lens. (A) (B) (C) d- 130 cm d- 190 em d2 = 210cm
Solution
12) from lens forrmula we get 1/v + 1/u = 1/f
Here u is object distance, v is image distance and f is focal length
Therefore, 1/10 + 1/5 =1/f
f=3.33 cm
Correct option is a
13)for the second lens, image from first lens is the object
Object distance=25-10=15 cm
Focal length=14 cm
Let image distance be v
1/15 + 1/v = 1/14
v=210 cm
Correct option is c