Question

what is the focal length of convex lens of equal radii​

Answer 1

Answer:

Focal length will be same as radii of lens.

Explanation:

Since

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

f= focal length

n= refractive index of lens(generally 1.5)

R1= radius 1

R2=radius 2

Given

R1 = R2 or -R1

Therefore

1/f= (1.5-1) [(1/R1) -(1/R2) ]

1/f= 0.5 [(1/R1) -(-1/R1) ]

1/f= 0.5 [(1/R1) + (1/R1) ]

1/f= 0.5 [(2/R1) ]

1/f= 1/R1

Therefore

f = R1