[填空题]
Two point charges of −4.0μC and 88.0μC a ogi w.c(ug 1v2vd,ff:refvj ;da1qkjdxpl ae23e53odw:28 .ft separated by a distance r=2.0cm as show d;xt32pj:o81jql d eadv f5w.a3e 2kfn in the diagram
1.State what is meant by electric field strength.
2.Calculate the magnitude of the electrostatic force exerted on each charge. F = N
3.Three points A, B and C are at the regions shown in the diagram.
(1)Deduce which point(s) could have zero electric field. Explain your reasoning.
(2)Calculate the distance(s) from charge q1 to the point(s) of zero electric field. X = cm
(3)The two charges are inserted in a water tank separated by the same distance as in air.The permittivity of water is 80 times that of free space.
Discuss what change, if any, will occur in the location of the point(s) of zero electric field in this case. Justify your answer.
4.The charges are removed from the water tank, and $q_1$ is replaced by another charge that is identical to $q_2$.
Point P is at equidistance d from both charges as shown.
Draw an arrow indicating the direction of the electric field at point P.
