When a conducting soap bubble is negatively charged then

Options

A. Its size starts varying arbitrarily
B. It expands
C. It contracts
D. No charge in its size takes place

Answer

To solve the problem of what happens when a conducting soap bubble is negatively charged, we can break down the explanation into several steps:

### Step-by-Step Solution:

1. **Understanding the Conducting Soap Bubble**:
- A soap bubble is a thin film of liquid surrounding a gas. When it is conducting, it allows charges to move freely across its surface.

2. **Charging the Soap Bubble**:
- When the soap bubble is negatively charged, negative charges (electrons) are added to its surface.

3. **Charge Distribution**:
- The negative charge will distribute itself evenly across the surface of the bubble due to the symmetry of the sphere. This is because like charges repel each other, and they will spread out to minimize repulsion.

4. **Effect of Repulsion**:
- The repulsive forces between the negative charges cause the surface of the soap bubble to expand. Each charge pushes away from the others, leading to an increase in the radius of the bubble.

5. **Equilibrium Condition**:
- The bubble will reach a new equilibrium radius where the electrostatic repulsive forces are balanced by the surface tension of the soap film. This means that the bubble will not just expand indefinitely but will stabilize at a new, larger radius.

6. **Conclusion**:
- Therefore, when a conducting soap bubble is negatively charged, its radius increases due to the repulsive forces between the like charges on its surface.

### Final Answer:
The radius of the conducting soap bubble increases when it is negatively charged.

---