Question

A plano convex lens of focal f length and radius R with refractive index n derive its lens makes formula​

Answer 1

Explanation:

Figure shows a plano-convex lens of refractive index μ=n.

From Lens Maker's formula

1/f=(u2/u1-1)(1/R1-1/R2)

where, μ2 and μ1 are refractive index of lens and surrounding medium respectively.

                    And,  R1  and R2 are radius of 1st and 2nd urfaces respectively.

Here, 

 μ1=1,μ2=n,R1=−∞,R2=−R,f=2R

hences

1/ef=(n-1))(1/infinite -1/-R)

1/f=(n-1)1/R

f=R/n-1