What happens to the power of a lens as its focal length decreases?

The power of a lens is defined as the ability of the lens to converge or diverge light and is calculated using the formula:

[ \text{Power (P)} = \frac{1}{\text{Focal Length (f)}} ]

This relationship indicates that the power of a lens is inversely proportional to its focal length. As the focal length decreases, the denominator in the equation becomes smaller, leading to a larger value for power. Therefore, when the focal length of a lens decreases, the power of the lens increases.

In optical terms, a lens with a shorter focal length means that it can bend light rays more sharply, resulting in a greater convergence for converging lenses or a quicker divergence for diverging lenses. This characteristic makes short-focal-length lenses useful in applications requiring high magnification, such as in microscopes or high-powered telescopes.

The aspects related to the other options illustrate that the power does not decrease, remain constant, or become irrelevant as the focal length changes. The precise relationship established by the power formula clarifies the direct link between focal length and the capability of a lens to affect light.