Physicshard · Past Paper
A convex lens forms a real image of a point object at a distance of 50 cm. If the object is at 50 cm, what is the power?
A+2 D
B+4 D
C+5 D
D+1 D
✓ Correct Answer: B — +4 D
u = -50cm, v = 50cm. 1/f = 1/50 - 1/(-50) = 2/50 = 1/25. f = 25cm = 0.25m. P = 1/0.25 = 4D.
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