Which of the following quantities can be measured using only a trayelling microscope

Options

A. Refractive index of a glass slab
B. Refractive index of a prism
C. Refracting angle of a prism
D. Refractive index a small drop of water

Explanation

To determine which quantities can be measured using only a traveling microscope, let's analyze the options provided in the question.

### Step-by-Step Solution:

1. **Understanding the Function of a Traveling Microscope**:
A traveling microscope is an optical instrument used for precise measurements of small distances and angles. It is particularly useful in experiments involving optics, such as measuring refractive indices.

2. **Option Analysis**:
- **Option 1: Refractive index of a glass slab**:
- The refractive index (μ) of a glass slab can be measured using a traveling microscope. This is done by measuring the thickness of the slab and the angle of incidence and refraction. Therefore, this option is correct.

- **Option 2: Refractive index of a prism**:
- To measure the refractive index of a prism, one typically uses a method involving the deviation of light and plotting a graph of deviation versus angle of incidence. While a traveling microscope can assist in measuring angles and distances, the complete setup requires additional apparatus. Thus, this option is not solely measured by a traveling microscope.

- **Option 3: Refractive index of a small drop of water**:
- Similar to the prism, measuring the refractive index of a small drop of water involves more complex setups, including the use of coherent light sources and specific geometrical arrangements. Therefore, this option is also not solely measured by a traveling microscope.

3. **Conclusion**:
Based on the analysis, the only quantity that can be measured using only a traveling microscope is the refractive index of a glass slab.

### Final Answer:
The quantity that can be measured using only a traveling microscope is the refractive index of a glass slab.

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