NEETPhysicsGeometrical OpticsMCQ+4 / −1
Two thin lenses are of same focal lengths , but one is convex and the other one is concave. When they are placed in contact with each other, the equivalent focal length of the combination will be :
- A
- B
- CInfinite
- DZero
View written solutionFree
Correct answer: C
$$\frac{1}{f_{e q}}=\frac{1}{f_{1}}+\frac{1}{f_{2}}$$
$$\frac{1}{f_{e q}}=\frac{1}{f}-\frac{1}{f}$$
$$\mathrm{f}_{\mathrm{eq}}=\infty$$
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