# Problem: A "biconvex" lens is one in which both surfaces of the lens bulge outwards. Suppose you had a biconvex lens with radii of curvature with magnitudes of |R1|=10cm and |R2|=15 cm. The lens is made of glass with index of refraction nglass=1.5. We will employ the convention that R1 refers to the radius of curvature of the surface through which light will enter the lens, and R2 refers to the radius of curvature of the surface from which light will exit the lens.A) What is the focal length of the lens if it is immersed in water (nwater = 1.3)f= ____________ cmB) What is the focal length f of this lens in air (index of refraction for air is nair=1)?

###### FREE Expert Solution

The lens equation:

$\overline{)\frac{\mathbf{1}}{\mathbf{f}}{\mathbf{=}}{\mathbf{\left(}}\frac{{\mathbf{\eta }}_{\mathbf{L}}}{{\mathbf{\eta }}_{\mathbf{m}}}{\mathbf{-}}{\mathbf{1}}{\mathbf{\right)}}{\mathbf{\left(}}\frac{\mathbf{1}}{{\mathbf{R}}_{\mathbf{1}}}{\mathbf{-}}\frac{\mathbf{1}}{{\mathbf{R}}_{\mathbf{2}}}{\mathbf{\right)}}}$, where ηL is the refractive index of the lens and ηm is the refractive index of the medium.

###### Problem Details

A "biconvex" lens is one in which both surfaces of the lens bulge outwards. Suppose you had a biconvex lens with radii of curvature with magnitudes of |R1|=10cm and |R2|=15 cm. The lens is made of glass with index of refraction nglass=1.5. We will employ the convention that R1 refers to the radius of curvature of the surface through which light will enter the lens, and R2 refers to the radius of curvature of the surface from which light will exit the lens.

A) What is the focal length of the lens if it is immersed in water (nwater = 1.3)
f= ____________ cm

B) What is the focal length f of this lens in air (index of refraction for air is nair=1)?