The Law of Conservation of Charge

1. Key Principle

• Charge cannot be created or destroyed, only transferred from one object to another.
• The total charge in an isolated system remains constant.

2. Charge Transfer Between Objects

a) When Two Charged Spheres Touch

• Electrons move from the sphere with more electrons to the one with fewer electrons.
• The total charge is shared between both spheres.

b) Formula for Final Charge on Each Sphere

$Q_{\text{total}} = Q_A + Q_B$

$Q_{\text{final}} = \frac{Q_{\text{total}}}{2}$

where:

• $Q_A$ and $Q_B$ are the initial charges.
• $Q_{\text{final}}$ is the charge on each sphere after contact.

c) Number of Electrons Transferred

$\text{No. of electrons} = \frac{\Delta Q}{e}$

where:

• $e = :highlight[1.6 × 10^{-19}]$ $C$ (charge of one electron).

4. Key Takeaways

✔ Total charge before and after contact remains the same.

✔ Electrons move from higher to lower electron concentration.

✔ Final charge on each object is the average of initial charges.

Exam Tip

💡 Use the correct signs for charges when solving problems!