A converging lens of focal length 15cm is used to obtain a real image magnified...
PHYSICS
WAEC 1997
A converging lens of focal length 15cm is used to obtain a real image magnified \(1\frac{1}{2}\) times. Calculate the distance of the image from the lens?
- A. 37.5cm
- B. 22.5cm
- C. 15cm
- D. 7.5cm
Correct Answer: A. 37.5cm
Explanation
If u=x, v = \(1\frac{1}{2}x \Rightarrow if u= 2x,v=3x\\
\frac{1}{f}=\frac{1}{u}+\frac{1}{v}; \frac{1}{15}=\frac{1}{2x}+\frac{1}{3x} \times \frac{5}{6}\\
X=\frac{75}{76}=12.5, v=3x=12.5\times 3=37.5\)
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