Question

The illuminance due to a 60.0-w lightbulb at 3.0m is 9.35 lx. What is the total luminous flux of the bulb

Answer 1

The equation for luminous flux is given as P = 4$\pi$$r^{2}$E
where P is the luminous flux, r is the distance and E is the illumination. The unit for P is lumen, E is lux and r is in meters. Substituting the given to the equation:

P = 4$\pi$$r^{2}$E 

P= 4$\pi$$(3)^{2}$(9.35) = 1057.46 lumens (lm)

The total luminous flux is equal to 1057.46 lumens (lm).