Question

 Find focal length & overall nature of the following silvered lenses. In all cases refractive index of material of lens is greater than that of surroundings. 

Answer 1

F_eff →-ive silvered lens behaves like concave mirror & nature is converging. 

Hence silvered lens behaves like concave mirror & nature is diverging 

 

F_eff = [R/2(2μ-1)] 

focal length of silvered lens is +ive hence its behaves like a convex mirror or its nature will be diverging. 

 

focal = +ive, hence silvered lens behaves like convex mirror or its nature will be diverging. 

hence the focal length of the silvered lens is –ive it behaves like concave mirror or converging

F_eq = -R/(μ+1)