Question 34
Lenses and Optical InstrumentsA man wears convex lens glasses of focal length 30 cm in order to correct his eye defect. Instead of the optimum 25 cm, his least distance of distinct vision is
- A.14 cm
- B.28 cm
- C.75 cm
- D.150 cm
Show the answer and explanation
Answer: D (150 cm)
Explanation
The lens must form a virtual image of an object at 25 cm at his near point: 1/30 = 1/25 − 1/v gives 1/v = 1/150, so his near point is 150 cm.