If the power of a lens is +1 Dioptre, then the focal length of the lens will be:  

The correct answer is +1 Dioptre.

Key Points

• The power of a lens (P) in dioptres is the reciprocal of the focal length (f) in meters, represented as P = 1/f.
• If the power of the lens is +1 Dioptre, the focal length (f) can be calculated using the formula: f = 1/P.
• Substituting the given power, f = 1/1 = 1 meter.
• A positive dioptre value indicates that the lens is a converging lens, typically used for correcting hyperopia (farsightedness).

Additional Information

• Dioptre (D): A unit of measurement for the optical power of a lens, defined as the reciprocal of the focal length in meters (1/m).
• Focal Length (f): The distance between the lens and the point where parallel rays of light converge (for a converging lens) or appear to diverge (for a diverging lens).
• Converging Lens: Also known as a convex lens, it bends light rays inward, bringing them to a focus. Used in applications like magnifying glasses and corrective lenses for hyperopia.
• Diverging Lens: Also known as a concave lens, it spreads out light rays that have been refracted through it. Used in applications like corrective lenses for myopia (nearsightedness).
• Hyperopia (Farsightedness): A condition where distant objects are seen more clearly than near ones. Converging lenses with positive dioptre values are used for correction.