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A point source emitting 628 lumen of lum...

A point source emitting 628 lumen of luminous flux uniformly in all directions is placed at the origin. Calculate the illuminance on a small area placed at (1.0 m, 0, 0) in such a way that the normal to the area makes an angle of `37^@` with the X-axis.

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The correct Answer is:
D
l=luminous intensity `=628/(4pi)=50 candela`
`r=1m, theta=37^@`
so ilumiN/Ance `e=costheta/r^2`
`=50xx(cos37^0)/1^2`
`=50x(4/5)/1=40lux`
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