A lens has a power of -4 D. What type of lens is it?
Practice Questions
Q1
A lens has a power of -4 D. What type of lens is it?
Convex lens
Concave lens
Bifocal lens
Plano-convex lens
Questions & Step-by-Step Solutions
A lens has a power of -4 D. What type of lens is it?
Correct Answer: Concave lens
Step 1: Understand what lens power means. Lens power is measured in diopters (D).
Step 2: Note that the power of the lens is given as -4 D.
Step 3: Recognize that a negative power indicates the type of lens.
Step 4: Remember that a lens with a negative power is a concave lens.
Step 5: Conclude that since the power is -4 D, the lens is a concave lens.
Lens Power – The power of a lens is the reciprocal of its focal length in meters. A negative power indicates a concave lens, while a positive power indicates a convex lens.
Types of Lenses – Lenses can be classified as concave (diverging) or convex (converging) based on their shape and the sign of their power.
