[单选题]
The diagram shows the equipoten
e7gj8-: q itsf /4lubwtial lines in a f
e2 w;+n nodcp o4mr(aii p:t ;k*n3imoi,.wo*ield due to A and B. What may be represented
otria*k;(i pmme +ndwcn3o* n4;: i 2ow.poi,by A and B?
I. 2 equal masses.
II. 2 equal charges of the same sign.
III. 2 equal charges of opposite sign
A. Only $I$
B. $ I$ and $III$ only
C. Only $III$
D. $ I$,$II$, and $III$
参考答案:
C
本题详细解析:
Explanation:
Equipotential lines are perpendicular to field lines, which means the field lines must be directed from A to B or vice versa. That is only possible for 2 charges with opposite sign. In I and II, the forces from the two objects would be in opposite directions, giving a resultant field zero at the midpoint, and equipotential lines of a “peanut” shape.