Radius of curvature and focal distance question?

[ChrisScience]

Radius of curvature and focal distance question?

Hi everyone! Really struggling on these two questions and have spent way too many hours coming up with the wrong answers. Below are the questions and my attempts. Any help would be greatly appreciated!


1. Calculate the radius of curvature of a lens with a focal distance of 40 cm and an index of 1.2.


2. An object placed 35 cm away from a lens projects a real image .55 m behind the lens. What is this lens’ focal distance?

 

[tiny-tim]

Hi ChrisScience! Welcome to PF!

What are the relevant equations?

Show us what you've tried, and where you're stuck, and then we'll know how to help!