Physics - Geometrical Optics Question with Solution | TestHub

PhysicsGeometrical OpticsRefraction at curved surface/LensEasy2 minPYQ_2020

PhysicsEasysingle choice

Two plano-convex lenses of focal lengths $20 cm$ and $30 cm$ are placed together to form a double convex lens. The final focal length will be

Options:

Answer:

Solution:

Equivalent focal length

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

$= \frac{1}{20} + \frac{1}{30}$

$∴ F = \frac{20 \times 30}{20 + 30}$

$= \frac{600}{50} = 12 cm$

Subject:PhysicsTopic:Geometrical OpticsSubtopic:Refraction at curved surface/Lens

⏱ 2mℹ️ Source: PYQ_2020

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