Question: User: Grade 12
Name:
Grade and Section:
Activity #2
Write TRUE if the statement is correct and FALSE if it is incorrect.
1. ____ Electrons have a negative charge.
2. ____ Protons have a positive charge.
3. ____ Neutrons have no net electric charge.
4. ____ Like charges attract each other.
5. ____ Unlike charges attract each other.
6. ____ Electric charge is measured in coulombs.
7. ____ An object becomes negatively charged when it gains electrons.
8. ____ An object becomes positively charged when it gains electrons.
9. ____ Electric charge can be transferred from one object to another.
10. ____ A neutral object has equal amounts of positive and negative charge.
Instructions: For each situation, identify whether the objects ATTRACT or REPEL.
1. (+) and (+) 12 ________
2. (-) and (-) 12 ________
3. (+) and (-) 12 ________
4. (-) and (+) 12 ________
5. (+) and neutral object 12 ________
Problem Solving
1. If $34500$ electrons were transferred to a neutral metal rod. What would be the electric charge of the metal rod?
2. What is the electric charge of $54.78$ moles of electrons?
1. **State the problem:**
We need to find the electric charge of a metal rod after transferring $34500$ electrons to it.
2. **Recall the formula for electric charge:**
$$Q = n imes e$$
where $Q$ is the total charge, $n$ is the number of electrons, and $e$ is the elementary charge of one electron.
3. **Important constants:**
The charge of one electron is $$e = -1.6 \times 10^{-19}$$ coulombs.
4. **Calculate the charge:**
$$Q = 34500 \times (-1.6 \times 10^{-19})$$
$$Q = -5.52 \times 10^{-15}$$ coulombs.
5. **Interpretation:**
The negative sign indicates the rod has gained negative charge.
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**Second problem:**
1. **State the problem:**
Find the electric charge of $54.78$ moles of electrons.
2. **Recall the formula:**
$$Q = n_e \times e$$
where $n_e$ is the total number of electrons.
3. **Calculate the total number of electrons:**
One mole contains Avogadro's number of particles:
$$N_A = 6.022 \times 10^{23}$$ electrons/mole.
So,
$$n_e = 54.78 \times 6.022 \times 10^{23} = 3.298 \times 10^{25}$$ electrons.
4. **Calculate the total charge:**
$$Q = 3.298 \times 10^{25} \times (-1.6 \times 10^{-19})$$
$$Q = -5.28 \times 10^{6}$$ coulombs.
5. **Interpretation:**
The charge is negative, indicating an excess of electrons.
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**Summary:**
- Charge of rod after $34500$ electrons transferred: $$-5.52 \times 10^{-15}$$ C
- Charge of $54.78$ moles of electrons: $$-5.28 \times 10^{6}$$ C