Question

You
are designing eye glasses got someone whose neR point is 100 cm.

A) neglecting the eye lens distance, what focal length lens
should you prescribe so that an object can clearly be seen when
placed at 25 cm in front of the eye? (Hint =25 cm and q= -100
cm)

B) what is the lens power in diopters?

Answer #1

**apply for diverging lens -1/f = 1/u + 1/v**

**u = object distance, = 25 cm**

**v= image distance = -100 cm**

**and f = focal length**

**magnifiication m = -(v/u) =y'/y ) =y'/y**

**f = uv/u+v**

**f = 25*-100/(25-100)**

**f = 33.34 cm is the focal length
-------<<<<<<<<<<<<Answer**

**------------------------------------------**

**Power P of a lens = 1/focal length in meter**

**Power P is measured in DIopters**

**so P = 1/0.3334**

**P = +3 Diopters
----------------------<<<<<<<<<<<<<<Answer**

**----------------------------------------**

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