A flat mirror revolves a constant angular velocity making n-0-4 revolutions per second- With what velocity -in ms-1- - will a light spot move along a spherical with a radius of 15 metres- the mirror is the centre of curvature of the screen-

Question

Toppr Admin · Accepted Answer

Correct option is D- -75-4-because- Angular velocity of mirror - -0-4rev-s-Rightarrow 0-4-times 2-pi-0-8-pi-rad-s-because- Angular velocity of reflected ray-Rightarrow 2-times 0-8-pi-1-6-pi-rad-s-Hence- velocity of light spot over the screen-v-rw-15-times 1-6-pi-75-4m-s-

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

Correct option is D. $$75.4$$
$$\because$$ Angular velocity of mirror = $$0.4rev/s$$
$$\Rightarrow 0.4\times 2\pi=0.8\pi\,rad/s$$
$$\because$$ Angular velocity of reflected ray
$$\Rightarrow 2\times 0.8\pi=1.6\pi\,rad/s$$
Hence, velocity of light spot over the screen
$$v=rw=15\times 1.6\pi=75.4m/s$$

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

Correct option is D. $$75.4$$$$\because$$ Angular velocity of mirror = $$0.4rev/s$$$$\Rightarrow 0.4\times 2\pi=0.8\pi\,rad/s$$$$\because$$ Angular velocity of reflected ray$$\Rightarrow 2\times 0.8\pi=1.6\pi\,rad/s$$Hence, velocity of light spot over the screen$$v=rw=15\times 1.6\pi=75.4m/s$$