Question

The radius of curvature of a Plano convex lens which has 2 refractive index is 20 cm by applying silver bromide on its surface to change concave mirror find focal length

Answer 1

Answer:

f = 0.2 m

Explanation:

given,                                        

refractive index (n) = 2                

Radius of curvature of ( R₁ ) = 20 cm

                                             = 0.2 m

Radius of curvature ( R₂ ) = ∞

Using lens maker formula                        

$\dfrac{1}{f} = (\mu - 1)(\dfrac{1}{R_1}-\dfrac{1}{R_2})$

$\dfrac{1}{f} = (2 - 1)(\dfrac{1}{0.2}-\dfrac{1}{\infty})$

$\dfrac{1}{f} = 1 \times (5- 0 )$

f = 0.2 m                                              

Hence, focal length of the concave mirror is equal to f = 0.2 m