If the radius of curvature of the curved surface of a plano-convex lens is 50 cm , its focal length is (μ = 1.5)

Question

If the radius of curvature of the curved surface of a plano-convex lens is 50 cm , its focal length is (μ = 1.5) (A) 0.5 m (B) 0.75 m (C) 0.25 m (D) 1 m

Tardigrade Admin · Accepted Answer

From lens maker's formula, (1/f)=(n - 1) ((1/R1) - (1/R2)) Given, n=1.5 R1=∞ (Plane surface) R2= -50 cm=-0.5 m (1/f)=(1.5 - 1)× (1/0.5) =0.5× (1/0.5)=1 m

Q. If the radius of curvature of the curved surface of a plano-convex lens is $50 c m$ , its focal length is $(μ = 1.5)$

$0.5 m$

$0.75 m$

$0.25 m$

$1 m$

From lens maker's formula,
$\frac{1}{f} = (n - 1) (\frac{1}{R _{1}} - \frac{1}{R _{2}})$
Given, $n = 1.5$
$R_{1} = \infty$ (Plane surface)
$R_{2} = - 50 c m = - 0.5 m$
$\frac{1}{f} = (1.5 - 1) \times \frac{1}{0.5}$
$= 0.5 \times \frac{1}{0.5} = 1 m$

Q. If the radius of curvature of the curved surface of a plano-convex lens is 50cm , its focal length is (μ=1.5)

0.5m

0.75m

0.25m

1m