A person cannot see distinctly objects kept beyond 2 m. This defect can be corrected by using a lens of power ___ D.

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Solution

The power of a lens is defined as the reciprocal of focal length, $P = \frac{1}{f}$ .
$H e r e, P = \frac{1}{2} m = 0.5 D$
The defect given in the question is short-sightedness, also called myopia. So, a concave lens must be used, therefore power should be –0.5 D.

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Q. A person cannot see distinctly objects kept beyond 2m. This defect can be corrected by using a lens of power

Q. A person cannot see distinctly objects kept beyond

2

m

. This defect can be corrected by using a lens of power:

Question 1
A person cannot see distinctly objects kept beyond 2 m. This defect can be corrected by using a lens of power

(a) + 0.5 D
(b) – 0.5 D
(c) + 0.2 D
(d) – 0.2 D

Question 1
A person cannot see distinctly objects kept beyond 2 m. This defect can be corrected by using a lens of power

(a) + 0.5 D
(b) – 0.5 D
(c) + 0.2 D
(d) – 0.2 D

Q. A person cannot see objects clearly beyond

50 cm .

What should be the power of corrective lens used ?

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A person cannot see distinctly objects kept beyond 2 m. This defect can be corrected by using a lens of power ___ D.

The power of a lens is defined as the reciprocal of focal length, P=1f. Here, P=12 m=0.5D The defect given in the question is short-sightedness, also called myopia. So, a concave lens must be used, therefore power should be –0.5 D.

The power of a lens is defined as the reciprocal of focal length, $P = \frac{1}{f}$ .
$H e r e, P = \frac{1}{2} m = 0.5 D$
The defect given in the question is short-sightedness, also called myopia. So, a concave lens must be used, therefore power should be –0.5 D.