A man wears convex lens glasses of focal length 30cm in order to correct his eye defect. instead of the optimum 25cm, his least distance of distinct vision is
- 14cm
- 28cm
- 75cm
-
150cm
The correct answer is: D
Explanation
F = \(\frac{uv}{u + v}\)
F = +ve
v = -ve
30 = \(\frac {25 {\times} (-v)}{25 + (-v)}\)
-25v = 750 - 30v
5v = 750
v = 150cm
(Note that either negative or positive values go to show the positioning and hence, they are not a strong necessity in your final answer.)