Charge problem in the second grade of junior high school

Let me tell you:

Two identical electroscopes mean that the total surface area of ??the metal foil, metal ball and connecting rod is equal.

If their metal balls are connected with a metal rod, according to the laws of physics, their charges should be evenly distributed.

One of the two electroscopes carries a larger charge and the other a smaller charge. If the charges are of the same kind, they will definitely take the middle value after being evenly distributed.

If it is a different type of charge, part of it will be offset. If the offset part is relatively large, the absolute value of both charges will become smaller.

For example, one is 8C and the other is -10C. After even distribution, 8C and -8C cancel out, leaving -2C. After bisection, both of them carry -1C, and the absolute values ??of both become smaller

If the offset part is relatively small, then the absolute value of the two charges becomes larger and the other smaller.

For example, one is 2C and the other is -10C. After even distribution, 2C and -2C cancel out, leaving -8C. After being divided equally, both of them will have -4C. The absolute value of one will become larger, and the absolute value of the other will become larger. become smaller.

So the absolute value of at least one of two electroscopes with unequal heterogeneous charges will become smaller after connecting the two metal balls.

This means that one angle may become larger or smaller, and the other angle must become smaller

So the answer is B

The "change" mentioned in the question "Situation" refers to what the angle between the two electroscopes becomes after they are connected with a metal rod.

To put it simply:

If two identical electroscopes carry unequal amounts of the same charge, the angle between one will become larger and the other will become smaller after connection

If two identical electroscopes carry unequal amounts of different charges, one of the angles may become larger or smaller after connection, and the other may become smaller

If two identical electroscopes carry equal charges For the same type of charge, the angle between the two remains unchanged after connecting

If two identical electroscopes carry the same amount of different charges, the angle between the two becomes 0 after connecting (metal foil not open), because equal amounts of different charges cancel out