Question

electric charge
the circles below represent electrically charged samples of matter. study the five samples and
answer the questions or complete the sentences that follow.

1. what do the pluses (+) and minuses (-) on the diagram represent?
2. which figure represents an electrically neutral sample?
3. why is the sample in question 2 neutral?
4. which figure or figures represent a negatively charged sample?
5. a sample of matter becomes negatively charged by gaining
6. negatively charged samples of matter have a greater number of

than

1. sample a could become neutral by
2. which two samples of matter could combine to form a neutral sample?
3. what is the charge on sample b?
4. what samples have identical charges?

Explanation:

1. What do the pluses (+) and minuses (-) on the diagram represent?

In the context of electric charge, the plus (+) represents protons (positively - charged particles) and the minus (-) represents electrons (negatively - charged particles).

2. Which figure represents an electrically neutral sample?

An electrically neutral sample has an equal number of positive and negative charges. In figure C, the number of + and - charges is the same.

3. Why is the sample in Question 2 neutral?

Because the number of protons (represented by +) is equal to the number of electrons (represented by -). Mathematically, if \(n_+\) is the number of + charges and \(n_-\) is the number of - charges, for a neutral sample \(n_+=n_-\).

4. Which figure or figures represent a negatively charged sample?

A negatively charged sample has more electrons ( - charges) than protons (+ charges). In figure B, there are more - charges.

5. A sample of matter becomes negatively charged by gaining...

Electrons. Since electrons are negatively - charged particles, gaining them increases the negative charge of the sample.

6. Negatively charged samples of matter have a greater number of...than...

Negatively charged samples have a greater number of electrons ( - charges) than protons (+ charges).

7. Sample A could become neutral by...

Sample A has \(n_+ = 5\) and \(n_-=3\). To become neutral (\(n_+=n_-\)), it needs to lose \(5 - 3=2\) protons (or gain 2 electrons).

8. Which two samples of matter could combine to form a neutral sample?

Let's calculate the net charge for each sample:

• Sample A: \(+2\) ( \(5\) + and \(3\) - )
• Sample B: \(-1\) ( \(3\) - and \(2\) + )
• Sample C: \(0\) ( \(4\) + and \(4\) - )
• Sample D: \(-2\) ( \(3\) - and \(1\) + )
• Sample E: \(+2\) ( \(4\) + and \(2\) - )

Sample A (\(+2\)) and Sample D (\(-2\)): \((+2)+(-2)=0\)

9. What is the charge on sample B?

Count the + and - charges. There are \(2\) + and \(3\) -. The net charge is \(2-3=-1\), so the charge is \(-1\) (negative).

10. What samples have identical charges?

Sample A (\(+2\)) and Sample E (\(+2\)) have the same charge.

Answer:

1. + represents protons and - represents electrons.
2. C
3. Because the number of protons equals the number of electrons.
4. B
5. electrons
6. electrons; protons
7. losing 2 protons (or gaining 2 electrons)
8. A and D
9. - 1 (negative)
10. A and E