A plane mirror of circular shape with radius `r=20cm` is fixed to the ceiling .A bulb is to be placed on the axis of the mirror.A circular area of radius `R=1m` on the floor is to be illuminated after reflection of light from the mirror. The height of the room is `3m` What is maximum distance from the center of the mirror and the bulb so that the required area is illuminated?

Answer

75 cm

Explanation

`DeltaABC ` & `DeltaAB'C`
`(x)/(0.20) = (x+3)/(1)`
x = 0.2x + 0.6`
`0.8x = 0.6 implies x = (3)/(4)` cm
x = 75 cm