What Should Be the Radius of Curvature of the Other Surface?

[lostfan176]

Homework Statement

A prescription for a corrective lens calls for +1.50 diopters. The lensmaker grinds the lens from a "blank" with n = 1.46 and a preformed convex front surface of radius of curvature of 19.0 cm. What should be the radius of curvature of the other surface?

Homework Equations

<br /> \frac{1}{f} = (n-1)\left ( \frac{1}{R_1} - \frac{1}{ R_2} \right ) <br />

The Attempt at a Solution

1.5=(1.46 - 1)(1/19 - 1/x)

(1.5/.46) - 1/19 = 3.208
-1/3.208 = -.3117

which is wrong
am i doing this right cause i don't think i am

 

[alphysicist]

Hi lostfan176,

One thing I see: the value in diopters of a lens is the inverse of the focal length in meters. When you wrote 1/f=1.5, you chose your units of length in meters, but then you wrote R1 in centimeters.