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An electric bulb illuminates a plane sur...

An electric bulb illuminates a plane surface. The intensity of illumination on the surface at a point 2 m away from the bulb `5 xx 10^-4` phot. The line joining the bulb to the point makes an angle of `60^@` with the normal to the surface. Calculate the luminous intensity of bulb.

A

30 cd

B

40 cd

C

20 cd

D

40 cd.

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