An object is kept at a distance of from a thin lens and the image formed is real

PHYSICS · Single correct · AP · Physics 2: Algebra-based · Geometric Optics · Geometric Optics

Problem

An object is kept at a distance of

16\ \text{cm}

from a thin lens and the image formed is real. If the object is kept at a distance of

6\ \text{cm}

from the same lens, the image formed is virtual. If the sizes of the images formed are equal, the focal length of the lens is (1)

19\ \text{cm}

(2)

17\ \text{cm}

(3)

21\ \text{cm}

(4)

11\ \text{cm}