GKFix MCQ Question

If the lens is equiconvex with radius R and is in air (n_air = 1), what is its focal length f_air?

• A. f_air = R / (n_lens - 1)
• B. f_air = R / (2 * (n_lens - 1))
• C. f_air = 2 * R / (n_lens - 1)
• D. f_air = (n_lens - 1) * R / 2