Answer :
Final answer:
The lens with a power of -4 D has a focal length of -25 cm, indicating that it is a concave lens, hence the answer B. 25 cm, concave lens is correct.
Explanation:
The power of a lens (P) is given as the inverse of the focal length (f), which is measured in meters. The formula for power is P = 1/f. Given the power of a lens is -4 D (diopters), we can find the focal length by rearranging the formula: f = 1/P.
So the focal length, f = 1/(-4 D) = -0.25 m or -25 cm. The negative sign indicates that the lens is of concave type, which diverges light rays. Therefore, the correct answer is B. 25 cm, concave lens.
