A biconvex lens has radii of curvature, 20 cm each. If the refractive index of the material of the lens is 1.5, the power of the lens is :

Question

A biconvex lens has radii of curvature, 20 cm each. If the refractive index of the material of the lens is 1.5, the power of the lens is : (A) infinity (B) +2 D (C) +20 D (D) +5 D

Tardigrade Admin · Accepted Answer

R 1= R 2=20 cm =0.2 m μ=(3/2) P =(1/ f )=(μ-1)((1/ R 1)-(1/ R 2)) <img class="img-fluid question-image" alt="image" src="https://cdn.tardigrade.in/img/question/physics/27989da2d0ad49982fdf308369813960-.png" /> P =((3/2)-1)((1/0.2)+(1/0.2)) P =(1/2)((2/0.2))=(10/2)=+5 D

Q. A biconvex lens has radii of curvature, $20 c m$ each. If the refractive index of the material of the lens is $1.5$ , the power of the lens is :

infinity

$+ 2 D$

$+ 20 D$

$+ 5 D$

$R_{1} = R_{2} = 20 c m = 0.2 m$
$μ = \frac{3}{2}$
$P = \frac{1}{f} = (μ - 1) (\frac{1}{R _{1}} - \frac{1}{R _{2}})$

$P = (\frac{3}{2} - 1) (\frac{1}{0.2} + \frac{1}{0.2})$
$P = \frac{1}{2} (\frac{2}{0.2}) = \frac{10}{2} = + 5 D$

Q. A biconvex lens has radii of curvature, 20cm each. If the refractive index of the material of the lens is 1.5, the power of the lens is :