Question

Find the refractive index of the glass which is a symmetrical convergent lens.If it's focal length is double of its radius of curvature of its surface

Answer 1

Answer:3/2

Step-by-step explanation:

Convex lens focal length=R

Symmetrical lens=Hence=R1=R2=R

By sigh conventions convex lens: R1=+R

R2= -R

Lens makers formula :

1/f=(n-1)[1/R1-1/R2]

1/R=(n-1)[1/R+1/R]

1/R=(n-1)[2/R]

1=2n-2

2n=3

n=3/2 =1.5

Answer 2

Answer:

Using formula: Lens Maker’s Formula:

f = focal length

R1 = radius of curvature of the lens surface closer to the source of light

R2 = radius of curvature of the lens surface farther to the source of light

n = Refractive index

Given: The lens is symmetrical. Therefore R1 = R2

According to sign convention: R1 = R & R2 = -R

focal length (f) = Radius of curvature(R)

2n-2 = 1

2n = 3

n = 3/2 = 1.5

n = Refractive index = 1.5

its correct answer