Q$10.$

a$)$ Explain the point by point method of lighting calculations

b$)$ A hall $30$ metres by $15$ metres with a ceiling height of $5$ metres is to be provided with a general illumination of $120$ lumens $\frac{?}{m^2}.$ Taking coefficient of utilization as $0\mathrm{.}5$ and depreciation factor of $1\mathrm{.}4,$ determine the following

a$.$ Total lumens required

b$.$ Total wattages required

c$.$ Number of fluorescent tubes required