Question

A convex lens of focal length 40 cm and a concave
lens of focal length 50 cm are placed in contact with
each other. Calculate (1) the power of the
combination and (ti) focal length of the combination.
1/2+12=3​

Answer 1

Explanation:

1/f eq=1/f1+1/f2 ; feq=f1×f2/f1+f2 ; feq=40×50/90=22.2cm ; P=1/feq =1/22.2=0.045D