Physicshard · Past Paper
The magnifying power of a telescope is 10 and its length is 110 cm. What are the focal lengths of the lenses?
A100 cm, 10 cm
B55 cm, 55 cm
C110 cm, 10 cm
D90 cm, 20 cm
✓ Correct Answer: A — 100 cm, 10 cm
m = fo/fe = 10 and L = fo + fe = 110. Solving gives fo = 100 cm and fe = 10 cm.
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