Question

An object is 1.6 m to the left of a lens of focal length 0.88 m. A second lens of focal length -2.6 m is 0.64 m to the right of the first lens. Find the distance between the object and the final image formed by the second lens.

Answer 1

1/u + 1/v = 1/f for

u = 1.6 cm

f = 0.88 cm

1/1.6 + 1/v = 1/0.88

v = 1.96 cm

So the image real inverted and diminished will be at a distance of 1.96 cm right from the convex lens.

So this seems to be a virtual object for the concave lens being at a distance 1.96 - 0.64 = 1.32 cm.

With f negative -2.6 cm and u that too negative -1.32 being virtual,

we can solve using once again 1/u + 1/v = 1/f

and solving we get v = 2.68 cm.

So the final image is real and inverted.

So the distance between object and the final image is 1.6 + 0.64 + 2.68 = 4.92 cm