Question

What is the focal length of double concave lens kept in air with two spherical surfaces radii R1= 20 cm and R2 = 40 cm. Take refractive index of lens n = $\frac{5}{3}$

• A. -20 cm
• B. 20 cm
• C. 40 cm
• D. -40 cm

Answer 1

Answer: (A)

-20 cm

Answer 2

The correct option is (A): -20 cm