Home › UP Board Class 10 › Physics › The Human Eye and the Colourful World › A myopic person uses a lens of focal length -1.5…
A myopic person uses a lens of focal length -1.5 m. The power of this lens is:
A-0.67 D
B+0.67 D
C+1.5 D
D-1.5 D
Answer & Solution
Correct answer: A. -0.67 D
1. Power of a lens P = 1 / f (with f in metres).
2. Given f = -1.5 m.
3. Substitute: P = 1 / (-1.5) = -0.6666... D.
4. Rounded to two decimals, P approx -0.67 D.
5. The minus sign confirms a diverging (concave) lens, as expected for myopia.
_Source: NCERT Class 10 Science Ch 11 'Human Eye and the Colourful World'_
Related questions
Light from a star changes colour during twinkling because:The ability of the eye to focus on objects at different distances is called:Tyndall effect — the visible path of a beam of light through a colloid — is a result of:An old man cannot read a book held close but can see distant scenes clearly. The defect anTwinkling of stars is caused by:The reddish appearance of the sun at sunrise and sunset is due to:The sky appears BLUE because of:A rainbow is formed by: