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Physics - Geometrical Optics Question with Solution | TestHub

PhysicsGeometrical OpticsRefraction at curved surface/LensEasy2 minPYQ_2020

PhysicsEasysingle choice

A screen is placed $90 cm$ from an object. The image of an object on the screen is formed by a convex lens at two different locations separated by $20 cm$ . The focal length of the lens is

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Answer:

Solution:

From displacement method

$D = 30 cm$ and $d = 20 cm$

$f = \frac{D^{2} - d^{2}}{4 D} \Rightarrow f = \frac{90^{2} - 20^{2}}{4 \times 90}$

$f = \frac{110 \times 70}{4 \times 90} \Rightarrow f = 21.4 cm$

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

⏱ 2mℹ️ Source: PYQ_2020

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