Charge Conservation: Definition and Examples for UK Physics

📚 Quick Study Guide

• ⚛️ Charge conservation states that the total electric charge in an isolated system never changes. Charge can neither be created nor destroyed.
• ➕ The net charge remains constant over time. If one object loses charge, another object gains an equal amount of charge.
• ⚡ Elementary charge ($e$) is the smallest unit of charge, approximately $1.602 × 10^{-19}$ Coulombs. All observable charges are integer multiples of this value.
• 🔬 Charge can be transferred between objects through various methods like conduction, induction, or friction.
• 💡 Examples of charge conservation include: radioactive decay, particle collisions, and circuit analysis.
• 📝 Mathematically, if $Q_{initial}$ is the initial total charge and $Q_{final}$ is the final total charge in a system, then $Q_{initial} = Q_{final}$.

🧪 Practice Quiz

1. What does the law of conservation of charge state?
   1. (A) Charge can be created but not destroyed.
   2. (B) Charge can be destroyed but not created.
   3. (C) The total charge in an isolated system remains constant.
   4. (D) The total charge in any system always increases.
2. If an object with a charge of +5C comes into contact with an object of -2C, what is the total charge after they reach equilibrium, assuming they form an isolated system?
   1. (A) +7C
   2. (B) -7C
   3. (C) +3C
   4. (D) -3C
3. Which of the following processes demonstrates the principle of charge conservation?
   1. (A) Heating a metal rod.
   2. (B) Radioactive decay.
   3. (C) Magnetizing a nail.
   4. (D) Boiling water.
4. What is the elementary charge (e) approximately equal to?
   1. (A) $9.11 × 10^{-31}$ C
   2. (B) $1.602 × 10^{-19}$ C
   3. (C) $6.626 × 10^{-34}$ C
   4. (D) $3.0 × 10^{8}$ C
5. Two initially neutral objects are rubbed together. Object A gains a charge of -3C. What is the charge on Object B?
   1. (A) -3C
   2. (B) +3C
   3. (C) 0C
   4. (D) -6C
6. In a nuclear reaction, a nucleus with a charge of +10e decays into two particles. If one particle has a charge of +4e, what is the charge of the other particle?
   1. (A) +14e
   2. (B) -6e
   3. (C) +6e
   4. (D) -14e
7. A closed system contains three charged particles: +2C, -5C, and +1C. What is the total charge of the system?
   1. (A) +8C
   2. (B) -8C
   3. (C) -2C
   4. (D) +2C