IIT JEE , AIEEE Forum - Physics , Mechanics

neeraj_agarwal_1990

An electric bulb is at a vertical distance h over the center of a circular table of radius R.By what factor the intensity of illumination at center O is greater than that at the edge of the table?

ans- $[{1+\frac{{R}^{2}}{{h}^{2}}} ^{\frac{3}{2}}$

snail

At the centre intensity

1/h^2 .....1

At edge intensity

1/(h^2+R^2) ......2

Dividing ..1 by ..2 we get

Ratio = 1+R^2/h^2

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