Question

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.

Answer 1

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 = 56.25 N/C

(觉得有不详细的地方,请指出)