A contact lens is made of plastic with an index of refraction of 1.58. The lens has a focal length of +28.0 cm | |
A contact lens is made of plastic with an index of refraction of 1.58. The lens has a focal length of +28.0 cm, and its inner surface has a radius of curvature of +23.0 mm. What is the radius of curvature of the outer surface?
Answers:
1use the lensmaker's equation:
1/f = (n0/n1 - 1)(1/r1 + 1/r2)
f is the focal length of the lens,
n0 is the refractive index of the lens material,
n1 is the refractive index of the medium the lens is in,
R1 is the radius of the lens closest to the light source,
R2 is the radius of the lens farthest from the light source
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if it's air where the lens is in... n0 = 1
1/[f(n0/n1 - 1)] = 1/r1 + 1/r2
1/[f(n0/n1 - 1)] - 1/r2 = 1/r1
1/r1 = 1/[28 cm (1.58 - 1)] - 1/(23 cm)
1/r1 = 1/(16.24 cm) - 1/(23 cm)
1/r1 = 0,018098093810237738273720282715785 cm^-1
r1 = 55,25 cm
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