45 The refractive index of a diverging meniscus lens is 1 5 and its radii of curvature are 20cm,25cm The - Physics - Ray Optics And Optical Instruments

Question

45 The refractive index of a diverging meniscus lens is 1 5 and its
radii of curvature are 20cm,25cm The focal power of lens
is----------

Rupak Bhattacharya · Accepted Answer

We knowfor diverging lens R1 is negative and R2 is positive  1f=(n-1)1R1-1R2          =0
5×-1 2-1 25=0 5×- 450 2×0 25=-4 5f=-22
2 cm    negative due to concaev diverging lens

45.The refractive index of a diverging meniscus lens is 1.5 and its radii of curvature are 20cm,25cm.The focal power of lens is----------