1% of light of a source with luminous intensi | vedclass

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Question

(B) The total luminous flux $\phi_{total}$ emitted by a source of luminous intensity $I_v = 50 \,cd$ is given by $\phi_{total} = 4\pi I_v = 4\pi 	ime

Vedclass · Accepted Answer

$200$

Vedclass · Answer

(B) The total luminous flux $\phi_{total}$ emitted by a source of luminous intensity $I_v = 50 \,cd$ is given by $\phi_{total} = 4\pi I_v = 4\pi 	imes 50 = 200\pi \,lumens$.The flux incident on the surface is $1\%$ of the total flux:$\phi_{incident} = \frac{1}{100} 	imes 200\pi = 2\pi \,lumens$.The area of the circular surface with radius $r = 10 \,cm = 0.1 \,m$ is:$A = \pi r^2 = \pi 	imes (0.1)^2 = 0.01\pi \,m^2$.The average illuminance $E$ is defined as the incident flux per unit area:$E = \frac{\phi_{incident}}{A} = \frac{2\pi}{0.01\pi} = \frac{2}{0.01} = 200 \,lux$.

$1\%$ of light of a source with luminous intensity $50 \,cd$ is incident on a circular surface of radius $10 \,cm$. The average illuminance of the surface is: (in $,lux$)

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