The focal length of a convex lens is 10 cm and its refractive index is 1.5 . If the radius of curvature of one surface is 7.5 cm , the radius of curvature of the second surface will be:

Question

The focal length of a convex lens is 10 cm and its refractive index is 1.5 . If the radius of curvature of one surface is 7.5 cm , the radius of curvature of the second surface will be: (A) 7.5 cm (B) 15 cm (C) 75 cm (D) 5 cm

Tardigrade Admin · Accepted Answer

(1/f)=(μ-1)((1/R1)-(1/R2)) (1/10)=(1.5-1)((1/7.5)-(1/ R 2)) (1/10)=(1/2)((1/7.5)-(1/R2)) R 2=-15 cm

Q. The focal length of a convex lens is $10 c m$ and its refractive index is $1.5.$ If the radius of curvature of one surface is $7.5 c m,$ the radius of curvature of the second surface will be:

7.5 cm

15 cm

75 cm

5 cm

$\frac{1}{f} = (μ - 1) (\frac{1}{R _{1}} - \frac{1}{R _{2}})$
$\frac{1}{10} = (1.5 - 1) (\frac{1}{7.5} - \frac{1}{R _{2}})$
$\frac{1}{10} = \frac{1}{2} (\frac{1}{7.5} - \frac{1}{R _{2}})$
$R_{2} = - 15 c m$

Q. The focal length of a convex lens is 10cm and its refractive index is 1.5. If the radius of curvature of one surface is 7.5cm, the radius of curvature of the second surface will be: