Page 2Answer Text Solution Answer : The prescribed lens is convex lens of focal length +0.67 m and the defect in vision is hypermetropia (farsightedness). Solution : Given: Power (P) =+1.5 D <br> To find: Focal length (f) <br> Formula: `P=(1)/(f(m))` <br> Calculation: From formula, <br> `f=(1.5)=+0.67 m` <br> The prescribed lens is convex lens as the focal length is positive. Convex lens has positive focal length and it is used for the correction of farsightedness or hypermetropia. Thus, the defect in vision is hypermetropia (farsightedness). Given P = +1.5 D Find out We need to find out the focal length of the given lens Solution f = 1/P Where, f is the focal length P is power f = 1/P = 1/+1.5 = 0.67 m. As the power of the lens is (+ve), the lens is converging.
Solve the following example. Given:Power of lens, P = +1.5 DNow, focal length of lens, \[f = \frac{1}{P} = + \frac{1}{1 . 5} = + 0 . 67 m\]Since, the focal length is positive, the lens prescribed for correction is convex lens. Thus, the defect of vision is farsightedness or hypermetropia. Concept: Eye Defect and its correction: Hypermetropia or far-sightedness Is there an error in this question or solution? |