Which of the following statements is false ?

Options

A. Kirchhoff's second law represents energy conservation
B. Wheatstone bridge is the most sensitive when all the four resistances are of the same order of magnitude
C. In a balanced Wheatstone bridge if the cell and the galvanometer are exchanged , the null points is disturbed
D. A rheostat can be used as a potential divider

Answer

To solve the question of identifying the false statement among the provided options, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Understand Kirchhoff's Second Law**:
- Kirchhoff's Second Law, also known as Kirchhoff's Voltage Law (KVL), states that the sum of the electrical potential differences (voltage) around any closed circuit is zero. This is based on the principle of conservation of energy.
- **Conclusion**: The first statement is true.

2. **Evaluate Wheatstone Bridge Sensitivity**:
- A Wheatstone bridge is most sensitive when all four resistances are of the same order of magnitude. When the resistances are equal, even a small change in resistance can cause a significant deflection in the galvanometer.
- **Conclusion**: The second statement is true.

3. **Examine the Effect of Exchanging Cell and Galvanometer**:
- If the galvanometer and the cell are exchanged in a Wheatstone bridge, the null point (the point where no current flows through the galvanometer) will not be disturbed. The balance condition remains unchanged regardless of the position of the galvanometer or the cell.
- **Conclusion**: The third statement is false.

4. **Check the Use of Rheostats**:
- Rheostats can indeed be used as potential dividers. They allow for the adjustment of resistance in a circuit, thereby enabling control over the voltage across different components.
- **Conclusion**: The fourth statement is true.

### Final Answer:
The false statement is **Option C**: "If we exchange the cell and galvanometer in the Wheatstone bridge, then the null point gets disturbed."

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