Precision of measurement depends on

Options

A. Least count of measuring instrument
B. Temperature of surrounding
C. Carefulness of observer
D. All of the above

Answer

To determine what the precision of measurement depends on, we can break down the factors involved in precision step by step.

### Step-by-Step Solution:

1. **Understanding Precision**:
- Precision refers to the degree of refinement in a measurement. It indicates how close the measurements are to each other when repeated under the same conditions.

2. **Role of the Instrument**:
- The precision of a measurement is primarily determined by the instrument used. Different instruments have different capabilities in terms of how finely they can measure.

3. **Least Count**:
- The least count of an instrument is the smallest value that can be measured accurately with that instrument. A smaller least count indicates higher precision. For example, a ruler with millimeter markings has a smaller least count than one with centimeter markings.

4. **Measurement Errors**:
- Precision is also influenced by measurement errors, which can arise from various sources. The two main types of errors are systematic errors and random errors.

5. **Observer Error**:
- The observer's technique can introduce errors, such as parallax error, which occurs when the observer's line of sight is not perpendicular to the measurement scale. This can lead to inaccurate readings.

6. **Environmental Factors**:
- Environmental conditions, such as temperature, can also affect precision. Instruments made of materials like metals can expand with temperature changes, leading to inaccuracies in measurements.

7. **Conclusion**:
- Therefore, the precision of measurement depends on the instrument used, the least count of that instrument, the observer's technique, and environmental factors such as temperature.

### Final Answer:
The precision of measurement depends on:
- The instrument used
- The least count of the instrument
- Observer-related errors (like parallax error)
- Environmental factors (like temperature)