Physics - Geometrical Optics Question with Solution | TestHub

PhysicsGeometrical OpticsRefraction at curved surface/LensEasy2 minPYQ_2020

PhysicsEasysingle choice

A point source of light is kept at a distance of $15 cm$ from a converging lens, on its optical axis. The focal length of the lens is $10 cm$ and its diameter is $3 cm$ . A screen is placed on the other side of the lens, perpendicular to the axis of the lens, at a distance $20 cm$ . from it. Then find the area of the illuminated part of the screen?

Options:

Answer:

Solution:

$\frac{1}{V} - \frac{1}{u} = \frac{1}{f} \Rightarrow \frac{1}{v} - \frac{1}{- 15} = \frac{1}{10} \Rightarrow \frac{1}{v} = \frac{1}{10} - \frac{1}{15}$

$\frac{1}{V} = \frac{3 - 2}{30} \Rightarrow v = 30 cm$

$for r, \frac{1.5}{30} = \frac{r}{10} \Rightarrow r = \frac{1}{2} cm \Rightarrow A = π r^{2} \Rightarrow A = π {(\frac{1}{2})}^{2}$

$A = \frac{π}{4} {cm}^{2}$

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

⏱ 2mℹ️ Source: PYQ_2020

Doubts & Discussion

Loading discussions...