What Determines the Charge of an Object in Electrostatic Induction?

[MIA6]

1. A body will maintain a constant negative electrostatic charge if the body
1) Maintains the same excess of electrons. 3) Continuously receives more electrons than it loses.
I chose 3) but I think both choices work. However, the correct answer is 1), I don’t why 3) is wrong.

2. Negatively charged rod A is used to charge rod B by induction. Object C is then charged by direct contact with rod B. The charge on object C
1) is positive 3) is negative.
I chose 3) because when negative charged rod A moves close to one end of rod B, the electrons in rod B would gather at the other end, so left the opposite end all positive. After that, when C comes to contact with rod B, it depends on which end it touches. I am little confused. If it touches the negative end, then C becomes negative; vice versa. But the answer was 1).

thanks for help.

 

[LowlyPion]

1. A body will maintain a constant negative electrostatic charge if the body
1) Maintains the same excess of electrons. 3) Continuously receives more electrons than it loses.
I chose 3) but I think both choices work. However, the correct answer is 1), I don’t why 3) is wrong.

2. Negatively charged rod A is used to charge rod B by induction. Object C is then charged by direct contact with rod B. The charge on object C
1) is positive 3) is negative.
I chose 3) because when negative charged rod A moves close to one end of rod B, the electrons in rod B would gather at the other end, so left the opposite end all positive. After that, when C comes to contact with rod B, it depends on which end it touches. I am little confused. If it touches the negative end, then C becomes negative; vice versa. But the answer was 1).

thanks for help.

1. The operative word is Constant. Unchanging. Stays the same.

2. If B's charge is affected by induction, it will be net positive and then it will be a sink for electrons when it is touched by C, imparting a net positive to C as well.

 

[MIA6]

2. If B's charge is affected by induction, it will be net positive and then it will be a sink for electrons when it is touched by C, imparting a net positive to C as well.

But induction is not conduction, why B will be net positive? If B is positive orginally, it's still postive; if it's negative, it will still be negative.

 

[LowlyPion]

But induction is not conduction, why B will be net positive? If B is positive orginally, it's still postive; if it's negative, it will still be negative.

A is negative. Induction makes B net positive. Touching neutral C to B makes C net positive too.

 

[MIA6]

A is negative. Induction makes B net positive. Touching neutral C to B makes C net positive too.

If B is net positive, where did some electrons in B go?