What is the power of a lens that has a focal length of 2 meters?

The power of a lens is calculated using the formula:

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

In this case, the focal length of the lens is 2 meters. Plugging this value into the formula gives:

[ \text{Power} = \frac{1}{2} = 0.50 \text{ D}. ]

This means that a lens with a focal length of 2 meters has a power of 0.50 diopters. The power indicates how strongly the lens converges or diverges light, with diopters being the unit of measurement. This result aligns with the answer provided, confirming that a focal length of 2 meters corresponds to 0.50 diopters of power.

To clarify the reasoning behind the other options, a focal length of 1 meter would yield a power of 1.00 D, while a shorter focal length would increase the power. Conversely, a longer focal length would result in a lower power. Hence, they do not apply in this context.