The light intensity of a source is 100 candelas. the illuminance on a surface is 4 lux. how far is the surface from the source?

a. 7 meters
b. 6 meters
c. 4 meters
d. 5 meters

To find the luminous intensity this formula is used;

Luminous intensity = illuminance ×  

∴ Lv = Ev ×

We know the luminous intensity is 100 candelas and the illuminance is 4 lux.

∴ 100 = 4 x  

∴ 100/4 =  

∴ 25 =  

∴ r =√25 = 5 meters

Therefore, the surface will be at a distance of 5 meters from the source.

the equation that correctly represent the reaction for formation of ammonia is

n2+ 3h2 → 2nh3 (answer d)

1 mole of nitrogen gas (n2) react with 3 moles of hydrogen gas (h2) to form 2 moles of ammonia ( nh3). this is in a process known as haber process were iron is used as a catalyst and reaction take place that a higher temperature and pressure. the process is exothermic hence energy is released.

i dont know the answe