Light from a point source in air falls on a convex spherical glass surface (μ=1.5 and radius of curvature =20 cm ). The distance of the light source from the glass surface is 100 cm. At what position the image is formed?

Question

Light from a point source in air falls on a convex spherical glass surface (μ=1.5 and radius of curvature =20 cm ). The distance of the light source from the glass surface is 100 cm. At what position the image is formed? (A) 60 cm (B) 80 cm (C) 100 cm (D) 120 cm

Tardigrade Admin · Accepted Answer

(μ2/v)-(μ1/u)=(μ2-μ1/R) ⇒ (1.5/v)-(1/(-100))=(1.5-1/(+20)) ⇒ v=+100 cm The image is formed at a distance of 100 cm from the glass surface in the direction of incident light.

Q. Light from a point source in air falls on a convex spherical glass surface $(μ = 1.5$ and radius of curvature $= 20 c m$ ). The distance of the light source from the glass surface is $100 c m$ . At what position the image is formed?

60 cm

80 cm

100 cm

120 cm

$\frac{μ _{2}}{v} - \frac{μ _{1}}{u} = \frac{μ _{2} - μ _{1}}{R}$
$\Rightarrow \frac{1.5}{v} - \frac{1}{( - 100 )} = \frac{1.5 - 1}{( + 20 )}$
$\Rightarrow v = + 100 c m$
The image is formed at a distance of $100 c m$ from the glass surface in the direction of incident light.

Q. Light from a point source in air falls on a convex spherical glass surface (μ=1.5 and radius of curvature =20cm ). The distance of the light source from the glass surface is 100cm. At what position the image is formed?