A thought experiment in Physics is one which is

Options

A. Theoretically possible but experimentally not feasible
B. Neither theoretically possible nor experimentally feasible
C. Performed by a non-physicist
D. Performed by a chemist

Answer

To solve the question about what a thought experiment in physics is, we can analyze the options provided and determine the correct definition step by step.

### Step-by-Step Solution:

1. **Understand the Concept of a Thought Experiment**:
A thought experiment is a hypothetical scenario used to explore the implications of a theory or principle. It is not conducted in a physical laboratory but rather in the mind.

2. **Evaluate the Options**:
- **Option 1**: Theoretically possible but experimentally not feasible.
- **Option 2**: Neither theoretically possible nor experimentally feasible.
- **Option 3**: Performed by a non-physicist.
- **Option 4**: Performed by a chemist.

3. **Analyze Option 1**:
This option states that a thought experiment is theoretically possible but cannot be conducted in practice. This aligns with the definition of a thought experiment, as it involves reasoning about a situation that cannot be physically tested.

4. **Analyze Option 2**:
This option suggests that the scenario is neither theoretically possible nor feasible. This does not align with the definition of a thought experiment, as it must have some theoretical grounding.

5. **Analyze Option 3**:
This option states that a thought experiment is performed by a non-physicist. While non-physicists can engage in thought experiments, this does not define what a thought experiment is.

6. **Analyze Option 4**:
This option suggests that a thought experiment is performed by a chemist. Similar to option 3, this does not define the concept of a thought experiment.

7. **Conclusion**:
Based on the analysis, the correct definition of a thought experiment in physics is given by **Option 1**: "theoretically possible but experimentally not feasible."

### Final Answer:
A thought experiment in physics is one which is theoretically possible but experimentally not feasible. Therefore, the correct answer is **Option 1**.

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