Question

The far point of a myopia eye is $1.5m$. To correct this defect of the eye, the power of lens is _______.

• A. $0.66D$
• B. $-0.66D$
• C. $+1.5D$
• D. $-1.55D$

Answer 1

Answer: (B)

$-0.66D$

Defect is Myopia means eye has problem in seeing far objects and thus concave lens is required for correction to shifts its far point from $1.5m$ to $\infty$. That means image of the object at infinty must be formed at $1.5m$ for the eye to view properly.

Since from the lens formula,

$\frac{1}{v}-\frac{1}{u}=\frac{1}{f}$

$u=-\infty ,v=-1.5m$

On solving, power of the lens required $P=\frac{1}{f}=-0.66D$