Physics - Geometrical Optics Question with Solution | TestHub

PhysicsGeometrical OpticsReflection at plane surfaceEasy2 minPYQ_2020

PhysicsEasysingle choice

A flat mirror revolves at a constant angular velocity making $n = 0.4$ revolutions per second. With what velocity (in $m s^{- 1}$ ) will a light spot move along a spherical screen with a radius of $15 m$ , if the mirror is at the centre of curvature of the screen?

Options:

Answer:

Solution:

$∵$ Angular velocity of the mirror $= 0.4 r e v s^{- 1}$

$= 0.4 \times 2 π = 0.8 π r a d s^{- 1}$

$∴$ Angular velocity of the reflected ray

$= 2 \times 0.8 π = 1.6 π ra d s^{- 1}$

Hence, the velocity of light spot over the screen

$v = r ω = 15 \times 1.6 π = 75.4 m s^{- 1}$

Stream:JEESubject:PhysicsTopic:Geometrical OpticsSubtopic:Reflection at plane surface

⏱ 2mℹ️ Source: PYQ_2020

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