Thin lens(urgent)

2007-06-02 1:13 am

1.A plano-convex lens having a focal length of 250mm is to be made of glass of refractive index n =1.520. Calculate the radius of curvature of the grinding and polishing tools that must be used to make this lens.

2.The radii of both surfaces of an equiconvex lens of index 1.60 are equal to 80mm. Find its power.

please help me to calculate.

回答 (1)

用戶40379

2007-06-02 2:46 am

✔ 最佳答案

Thin lens(urgent)
1.A plano-convex lens having a focal length of 250mm is to be made of glass of refractive index n =1.520. Calculate the radius of curvature of the grinding and polishing tools that must be used to make this lens.
(1/f) = (n – 1)(1/R)
1 / 250 = (1.520 – 1)(1/R)
R = (1.520 – 1) x 250
R = 130mm

2.The radii of both surfaces of an equiconvex lens of index 1.60 are equal to 80mm. Find its power.
(1/f) = (n – 1)[(1/R1) + (1/R2)]
(1/f) = (1.6 – 1)[(1/80) + (1/80)]
f = 66.7mm = 0.0667m
power = 1/f = 1 / 0.0667
= 15D

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