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? 發問於 科學及數學其他 - 科學 · 1 十年前

# 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.

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

### 1 個解答

• ?
Lv 7
1 十年前
最愛解答

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