Physics · Geometrical Optics

JEE Main 2025 — 7 April, Morning Shift — Question 53

Two thin convex lenses of focal lengths 30 cm and 10 cm are placed coaxially, 10 cm apart.

The power of this combination is:

Answer: A

For parallel range $\frac{1}{F}=\frac{1}{F_{1}}+\frac{1}{F_{2}}-\frac{d}{F_{1} F_{2}}$

$\Rightarrow \frac{1}{F}=\frac{1}{30}+\frac{1}{10}-\frac{10}{10 \times 30}=\frac{1}{10}$

$\Rightarrow \quad F=\left(\frac{1}{10}\right) \mathrm{m}$

So, power $P=\frac{1}{F}=10 \mathrm{D}$

Answer key and solution verified before publishing.

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