Question

If kavita from 10th using spectacles .The power of the lenses in her spectacles is 2.5 dioptre then ,
1.which lenses are used in spectacles?
2.state the defect of vision kavita is suffering from?
3.find the focal length of lenses used in her spectacles

Answer 1

Power = P = 2.5D

1. The lenses are convex as the power is positive.

2. Kavitha is suffering from farsightedness or hypermetropia.

3. By formula,

P = 1 / f

2.5 = 1 / f

∴ f = 1 ÷ 2.5

∴The focal length of lenses used in her spectacles is 0.4