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Physics - Geometrical Optics Question with Solution | TestHub

PhysicsGeometrical OpticsRefraction at curved surface/LensEasy2 minPYQ_2020

PhysicsEasysingle choice

A convex lens $A$ of focal length $20 c m$ and a concave lens $B$ of focal length $5 c m$ are kept along the same axis with a distance $d$ between them. If a parallel beam of light falling on $A$ leaves $B$ as a parallel beam, then the distance $d$ (in $c m$ ) will be

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Answer:

Solution:

$\frac{1}{F} = \frac{1}{f_{1}} + \frac{1}{f_{2}} - \frac{d}{f_{1} f_{2}}$

$∴ \frac{1}{\infty} = \frac{1}{20} + \frac{1}{- 5} - \frac{d}{20 (- 5)}$

$\Rightarrow 0 = \frac{1}{20} - \frac{1}{5} + \frac{d}{100}$

$∴ \frac{d}{100} = \frac{1}{5} - \frac{1}{20} = \frac{20 - 5}{100}$

$∴ d = 15 c m$

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

⏱ 2mℹ️ Source: PYQ_2020

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