What is the refraction index of the material of a plano-convex lens, if the radius of curvature of the convex surface is 10 cm and focal length of the lens is 30 cm ?

Question

What is the refraction index of the material of a plano-convex lens, if the radius of curvature of the convex surface is 10 cm and focal length of the lens is 30 cm ? (A) (1/3) (B) 1 (C) (4/3) (D) (2/3)

Tardigrade Admin · Accepted Answer

<img class="img-fluid question-image" alt="image" src="https://cdn.tardigrade.in/img/question/physics/65a4ea15555297fcff96c5b265599292-.png" /> R1 =∞ R2 =-10 cm f =30 cm μ =? (1/f) =(μ-1)((1/R1)-(1/R2)) (1/30) =(μ-1)((1/∞)-(1/-10))=(μ-1/10) μ =1+(1/3)=(4/3)

Q. What is the refraction index of the material of a plano-convex lens, if the radius of curvature of the convex surface is $10 c m$ and focal length of the lens is $30 c m$ ?

$\frac{1}{3}$

$1$

$\frac{4}{3}$

$\frac{2}{3}$

$R_{1} = \infty$
$R_{2} = - 10 c m$
$f = 30 c m$
$μ = ?$
$\frac{1}{f} = (μ - 1) (\frac{1}{R _{1}} - \frac{1}{R _{2}})$
$\frac{1}{30} = (μ - 1) (\frac{1}{\infty} - \frac{1}{- 10}) = \frac{μ - 1}{10}$
$μ = 1 + \frac{1}{3} = \frac{4}{3}$

Q. What is the refraction index of the material of a plano-convex lens, if the radius of curvature of the convex surface is 10cm and focal length of the lens is 30cm ?

31​

1

34​

32​

R1​=∞ R2​=−10cm f=30cm μ=? f1​=(μ−1)(R1​1​−R2​1​) 301​=(μ−1)(∞1​−−101​)=10μ−1​ μ=1+31​=34​

Q. What is the refraction index of the material of a plano-convex lens, if the radius of curvature of the convex surface is $10 c m$ and focal length of the lens is $30 c m$ ?

$\frac{1}{3}$

$1$

$\frac{4}{3}$

$\frac{2}{3}$

$R_{1} = \infty$
$R_{2} = - 10 c m$
$f = 30 c m$
$μ = ?$
$\frac{1}{f} = (μ - 1) (\frac{1}{R _{1}} - \frac{1}{R _{2}})$
$\frac{1}{30} = (μ - 1) (\frac{1}{\infty} - \frac{1}{- 10}) = \frac{μ - 1}{10}$
$μ = 1 + \frac{1}{3} = \frac{4}{3}$