If a concave lens has a focal length of -15 cm, what is its power?

If a concave lens has a focal length of -15 cm, what is its power?

Step 1: Understand that the focal length (f) of the lens is given as -15 cm. The negative sign indicates that it is a concave lens.
Step 2: Convert the focal length from centimeters to meters. Since 1 cm = 0.01 m, -15 cm = -0.15 m.
Step 3: Use the formula for power (P) of a lens, which is P = 1/f, where f is the focal length in meters.
Step 4: Substitute the focal length into the formula: P = 1/(-0.15).
Step 5: Calculate the power: P = -6.67 D (diopters). The negative sign indicates that it is a concave lens.

Lens Power – The power of a lens is the reciprocal of its focal length, measured in meters. For concave lenses, the focal length is negative, resulting in a negative power.