Physics - Geometrical Optics Question with Solution | TestHub

PhysicsGeometrical OpticsRefraction at curved surface/LensEasy2 minPYQ_2020

PhysicsEasysingle choice

A converging lens having magnitude of focal length as $f_{1}$ is kept coaxially in contact with a diverging lens having magnitude of focal length as $f_{2}$ . The focal length of the combination would be:

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Answer:

Solution:

We have to consider sign convention as only magnitude of focal length is given.If $f_{1}$ is focal length of convex (converging) lens and $f_{2}$ is focal length of concave (diverging) lens. Then their equivalent focal length F would be $\begin{array}{l} \frac{1}{F} = \frac{1}{f_{1}} + \frac{1}{- f_{2}} = \frac{f_{2} - f_{1}}{f_{1} f_{2}} [∵ \frac{1}{F} = \frac{1}{f_{1}} + \frac{1}{f_{2}}] \\ ∴ F = \frac{f_{1} f_{2}}{f_{2} - f_{1}} \end{array}$

Stream:NTA_ABHYAS_NEETSubject:PhysicsTopic:Geometrical OpticsSubtopic:Refraction at curved surface/Lens

⏱ 2mℹ️ Source: PYQ_2020

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