SSE JE Electrical Engineering 10 Dec 2020 Papers

C.P
Illumination
$\mathrm{\omega }=\frac{\mathrm{A}}{{\mathrm{R}}^2}$
Where R = distance of the point from the point of source.
In the given problem R = height at which the lamp is suspended.
$\mathrm{C}.\mathrm{P}=\mathrm{\varphi }\times \frac{{\mathrm{R}}^2}{\mathrm{A}}$
$\mathrm{C}.\mathrm{P}=\mathrm{I}\times {\mathrm{R}}^2$
$180=80{\mathrm{R}}^2$
$\mathrm{R}=\frac{3}{2}=1.5$ meters.