Notes

Lens Formula…

Lens Formula – focal length of the lens is given by,
1/f = (μ2/ μ1 – 1) (1/ R1 – 1/ R2)
where, R1 and R2 are the radii of curvature of first and second refracting surfaces of a thin lens, f is the focal length and μ is refractive index of material of lens with respect to surrounding medium as shown in the figure given below.
If μ2 and μ1 = 1, then
⇒ [1/f = (μ – 1) (1/R1 – 1/R2)]
This is called lens maker Formula. Lens maker formula is used to design lenses of desired focal length.
Lens formula is given by
1/v – 1/u = 1/f