Question

Biconcave lens has radii of curvature 10cm each. if refractive index of the material of lens os 1.5 then focal lenght of lens is

Answer 1

we know the formula1/f=R.I(-1)(1/R1-1/R2)1/f=1.5(-1)(1/10-(-1/10))1/f=-1.5(1/5)f=0.3