A man wears convex lens glasses of focal length 30cm in order to correct his...
PHYSICS
JAMB 1998
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
- A. 14cm
- B. 28cm
- C. 75cm
- D. 150cm
Correct Answer: A. 14cm
Explanation
F = \(\frac{uv}{u - v}\)
F = +ve
v = -ve
30 = \(\frac {25 {\times} (-v)}{25 - (-v)}\)
v = \(\frac {25 {\times} (-v)}{25+v}\)
v = 14cm
(Note that either negative or positive values go to show the positioning and hence, they are not a strong necessity in your final answer.)
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