点电荷Q的电场中,A的场强为100N/C,C点的场强为36N/C,B是AC中点,且ABC在同一直线上,求B的电场强度.

题目

点电荷Q的电场中,A的场强为100N/C,C点的场强为36N/C,B是AC中点,且ABC在同一直线上,求B的电场强度.
怎么求

答案

E = kQ/r^2 A 点:E = 100 = kQ/r^2 C 点:E'= 36 = kQ/r'^2 100/36 = (r'/r)^2 r'/r = 5/3 B 点处 r'' = (r + r')/2 = (r + 5r/3)/2 = 4r/3 E'' = kQ/r''^2 E''/E = (r/r'')^2 = (3/4)^2 = 9/16 E'' = (9/16)*100 = 5...