7 A light bulb hangs from the ceiling at height A metres above the Floor , directly above point N . At any point A on the floor which ceiling is I metres from the light bulb , the illumination I is given by I A light bulb I = VB cost units . a If NA = 1 metre , show that at A. I = V/ 8 cosa sin 2 0. 6. The light bulb may be lifted or lowered to change the intensity at A. Assuming NA = 1 metre , find the height the bulb should be above the floor for greatest illumination floor at AL. M A`