In the searle's experiment, after every step of loading, why should we wait for two minutes before taking the reading?( More than one options may be correct).

Options

A. So that the wire can have its desired change in length
B. So that the wire can room temperature
C. So that vertical oscillations can get subsided
D. So that the wire has no change in its radius.

Answer

To answer the question "In Searle's experiment, after every step of loading, why should we wait for two minutes before taking the reading?", we can analyze the reasons step by step.

### Step-by-Step Solution:

1. **Understanding the Experiment**: In Searle's experiment, we are dealing with a metal wire that is subjected to different loads. The primary goal is to measure the change in length of the wire as different weights are applied.

2. **Reason for Waiting**: The first reason for waiting two minutes is to allow the wire to reach its desired change in length after a load is applied. When a weight is added to the wire, it stretches, but this change does not happen instantaneously. The wire needs time to adjust to the new load and stabilize.

- **Conclusion**: This means that the first option (the wire can have its desired change in length) is correct.

3. **Temperature Stabilization**: When a load is applied to the wire, it can cause a slight increase in temperature due to internal friction and deformation. This temperature change can affect the material properties of the wire. Waiting for two minutes allows the wire to reach a stable temperature before taking measurements.

- **Conclusion**: Thus, the second option (so that the wire can have the same temperature) is also correct.

4. **Damping Oscillations**: When the load is applied, the wire may oscillate slightly before coming to rest. This oscillation can lead to inaccurate readings if taken immediately. Allowing time for the wire to settle ensures that we measure the final, stable length.

- **Conclusion**: Therefore, the third option (so that the vertical oscillations can subside) is also correct.

5. **Incorrect Option**: The fourth option suggests that we wait to ensure that the wire does not change its cross-sectional area. However, the cross-sectional area of a wire does change when it is stretched under load, and this is a normal behavior of materials under tension. Thus, this option is incorrect.

- **Conclusion**: The fourth option is not correct.

### Final Answer:
The correct reasons for waiting two minutes before taking the readings in Searle's experiment are:
- The wire can have its desired change in length.
- The wire can have the same temperature.
- The vertical oscillations can subside.

Therefore, options 1, 2, and 3 are correct.

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