In meter brigde of Wheatstone bridge for measurment of resistance, the known and the unknown resistance are interchanged. The error so removed is

Options

A. end correction
B. index error
C. due to temperature effect
D. random error

Answer

To solve the problem regarding the error removed when the known and unknown resistances are interchanged in a meter bridge (Wheatstone bridge), we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Meter Bridge**:
A meter bridge is a device used to measure unknown resistances by balancing two legs of a bridge circuit. It consists of a wire of uniform cross-section and known length (1 meter) and a galvanometer to detect the null point.

2. **Identifying the Error**:
In a typical meter bridge setup, it is assumed that the resistance of the connecting wires and the bridge itself is negligible. However, this is not entirely true, and there exists a small resistance in the bridge wire, which leads to an error in the measurement. This error is known as "end error."

3. **Interchanging Known and Unknown Resistances**:
When the known resistance (R) and the unknown resistance (X) are interchanged, the balance point shifts. By taking readings with both configurations (R in place of X and vice versa), we can average the readings to minimize the effect of the end error.

4. **Calculating the Mean Reading**:
When the resistances are interchanged, we can denote the balance lengths as L1 (for known resistance) and L2 (for unknown resistance). The mean reading can be calculated as:
\[ L_{mean} = \frac{L1 + L2}{2} \]
This mean value helps in compensating for the end error.

5. **Conclusion**:
By interchanging the known and unknown resistances and taking the mean of the readings, the end error is effectively removed, leading to a more accurate measurement of the unknown resistance.

### Final Answer:
The error that is removed by interchanging the known and unknown resistances in a meter bridge is the "end error."

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