Acharge Q=7nc,is located at(-0.2,-0.3,0.6)in air,find the magnitude of electric field intensity at point 1m?

Answer 1

Your question is unclear when it refers to a "point 1m." However, I can tell you that the magnitude of the electric field intensity is ||E|| = Q / (4*pi*ε*r^2), where Q is the magnitude of the charge (which would be 7 x 10^-9 C), ε is the permittivity of air (which is close enough to ε0, the permittivity of free space, that you can just use ε0 (you should have the value in your textbook) here), and r is the distance from the charge to the point of interest. If a "point 1m" means a point 1 meter from the charge, use r = 1. However, that seems unlikely because then you wouldn't need the coordinates of the charge. If you have the coordinates of the point of interest, the distance between them is found using the 3-D distance formula, r = sqrt((x1 - x2)^2 + (y1 - y2)^2 + (z1 - z2)^2).