If a lens has a focal length of 2 meters, what is its power in diopters?

The power of a lens in diopters can be calculated using the formula:

[ \text{Power (D)} = \frac{1}{\text{Focal Length (m)}} ]

In this case, the focal length of the lens is given as 2 meters. To find the power, you would substitute the focal length into the formula:

[ \text{Power} = \frac{1}{2} = 0.5 \text{ Diopters} ]

This calculation shows that a lens with a focal length of 2 meters indeed has a power of 0.5 diopters. The diopter is a unit of measurement that indicates the optical power of a lens, with higher values indicating stronger lenses that can bend light more significantly.

The other values do not fit the calculation based on the provided focal length. Thus, the answer of 0.5 diopters is confirmed by the proper use of the formula for calculating lens power.