1. An object 20.0 cm to the left of a convex lens is 1.0 m in height. What is th

Question

1. An object 20.0 cm to the left of a convex lens is 1.0 m in height. What is the height and location of its image if the lens has a magnification of -2.0? Answer in units of m and also how many cm on the left/ right side of the lens.

2. Imagine you are nearsighted (can only see close objects clearly and far objects are blurry). At your last eye doctor's appointment, your optomotrist tells you that she will need to increase your prescription because as it turns out light is focusing "too soon" or in front of your retina. You respond, "Obviously, I will need a converging/ diverging lens with a higher/ lower focal distance."

Explanation / Answer

1) given data

focal length, f = 20 cm

let u and v are the object and image distances.

magnification, m = -v/u

-2 = -v/u

v = 2*u

now Apply,

1/u + 1/v = 1/f

1/u + 1/(2*u) = 1/f

(1/u)*1.5 = 1/20

u = 20*1.5

= 30 cm

so, image distance, v = 2*30

= 60 cm right side of the lense. <<<<<<<------------Answer

height of the image = m*height of object

= 2*1

= 2 m <<<<<<<------------Answer

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