Two convex lenses with power 2 dioptre are kept in contact with each other. The focal length of the combined lens system is

- 0.10 m
- 2 m
- 4 m
- 0.25 m

### Answer

The power of combination of lenses is the algebraic sum of the powers of individual lenses.

P = P_{1} + P_{2} = 4 m

1/f = 1/f_{1} + 1/f_{2}

f = 1/4 = 0.25 m

**The correct option is D.**