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**1. Homework Statement**

A plane convex lens is made of glass (index 1.42) with one flat surface and the other having a radius of 24 cm. What is the focal length of the lens? Anwer in united of cm.

**2. Homework Equations**

Lensmaker Equation

1/f=(n-1)*((1/r1)-(1/r2))

**3. The Attempt at a Solution**

f=1/[(n-1)*(1/r1)-(1/r2))]

f=1/[(1.42-1)*((1/-24cm)-(1/0))]

f=-57.142857

Is this right?? If the surface is flat on the lens, radius is given as 0 then correct? please check my work.