Aparticle with charge 8 µc is located on the x-axis at the point −10 cm , and a second particle with charge 3 µc is placed on the x-axis at −8 cm . −10−8 −6 −4 −2 2 4 6 8 10 8 µ c 3 µ c − 3 µ c x → (cm) what is the magnitude of the total electrostatic force on a third particle with charge −3 µc placed on the x-axis at 2 cm

The illuminance of a surface varies inversely with the square of its distance from the light source. if the illuminance of a surface is 120 lumens per square meter when its distance from a certain light source is 6 meters, by how many meters should the distance of the surface from the source be increased to reduce its illuminance to 30 lumens per square meter?